While I can understand why Automation isn't much of a thing in base Minecraft, one of the main problems I find myself noticing is that mods that do add automation tend to go a little bit overboard. Very few of them fit well with the base game, and it tends to force players to end up choosing between the vanilla game, and automation mods that replace the base game entirely. 'Create' is the one mod I've found thus far that at least has something of a Vanilla aesthetic- but this too changes the game so drastically that it becomes more about the mod than the base game.
Something I would be interested would be a mod that implements simple, Vanilla style additions to the game that allow for more modification, without breaking or drastically changing the game. Primarily, this would be in hopes of offering alternative solutions for some of the weirder bits of automation in the game- Automation does exist in Vanilla, but it tends to be pretty exploit-laden. (At least in my opinion.) Many of these ideas are present as small additions offered by larger mods- but it would be neat if there was an all encompassing 'Automation Update' so to speak, that added a bunch of helpful additions with a similar, vanilla-esque* aesthetic and mechanics. These are all general, conceptual ideas. I'm by no means a programmer of game developer, and am aware that balancing this sort of thing is far from easy. This is mostly just how I would consider going about adding an automation mechanic to the game.
*(By which I mean sharing an aesthetic similar to Vanilla- that is, new components could have a similar appearance to existing automation and redstone mechanics such as pistons, furnaces, etc.)
Conveyor Belts are a means of moving items and blocks around very quickly. They are crafted with three wool in the top row, two iron ingots and one redstone dust in the middle row, and three cobblestone in the bottom row. (This recipe makes Three Conveyor belts.) These can be used to visibly move items, blocks and even mobs in a specific direction. Conveyor belts can be dyed to make logistics easier to see, and stop moving when they recieve a redstone signal. Comperators release signals from conveyor belts with an item, block, or entity on it. Like stairs, conveyor belts connect to adjacent conveyor belts of the same color. The block itself is slightly shorter than a regular block, with the belt set into the top, and animated in order to show which direction its pumping. It would be cool if blocks appeared as scaled down versions of their in-game model when on a conveyor belt- (That is, if their models were the size of player heads when carried on belts.) Conveyor belts can dump their contents directly onto a hopper. Importantly, they are cheaper to make than a chest-minecart system. And look nicer, besides.
Vertical Belts are exactly what the name implies. They can move blocks, items, and mobs directly upwards, but are slightly more expensive than normal belts. Like normal belts, they visibly lift things upwards, can be measured by comperators. These would not be elevators, and would strictly only work for blocks, items, and smaller entities.
Item Pipes can move items, but not blocks. They're also slower than conveyor belts, but are easier to craft. I like how Quark goes about doing item pipes- that is, like many of Minecraft's mechanics, the pipes introduced by said mod have mechanics determined by how they're placed rather than what 'modules' are input into them. In this way, only one new thing has to be added rather than a dozen needlessly complicated ones. Items try and move downwards, move randomly when confronted with a junction, move straight if possible, and can be inserted into hoppers and fed by hoppers. Similar to Quark, one glass pane and two iron nuggets could make an item pipe.They break if too many items are stored inside, and can also interact with comperators/deactivate if they receive a redstone signal.
Junctions are blocks that can separate and merge conveyor belts, but not item pipes. A Seperator is a redstone block that can take in a single conveyor belt input, and split it into three separate outputs. A Merger is a redstone block that can take in up to three conveyor belt inputs, and merge it into a single output. Like pipes, these blocks break if they become overloaded. also like pipes, redstone signals lock these blocks. Each of them has four visible input slots on each side, and an emblem on the top that shows what type it is. Both would be made using a single piston, cobblestone, and two redstone dust in a different arrangement. They can also feed directly into other junctions, as well as droppers and dispensers.
Sorters are a useful type of redstone circuit that can be placed directly next to a conveyor built- similar to the sorting mechanics of Create, they can hold a single item, and will then act sort of like a piston, pushing the same type of item off the Conveyor belt whenever it occurs adjacent to it on the Conveyor. Like all the previously mentioned blocks, a redstone signal disables this block. It can also be fed an item by hoppers, and its item can be retrieved with a hopper- allowing for really complex logistics if that's your thing.
Magnets are a unique block that draws items towards it when activated- however, it isn't cheap, requiring a Netherite ingot, iron, and redstone to craft. (This is somewhat going off the other magnetic properties of Netherite that the Lodestone illustrates.)
Autocrafting is something that I doubt was ever intended to be implemented in a game that is literally all about crafting... but I think it is possible to implement without breaking the game, and without completely moving away from Vanilla aesthetics.
Autocrafter ~ This expensive block is integral to automatically crafting things. The recipe for this block consists of a diamond, two pistons, an item frame, two redstone, and three cobblestone. It has a sort of redstone-item frame on top of it, which can be fed by a conveyor belt, hopper, or player interaction. When enough Autocrafters are adjacent, and they're supplied with resources that form a crafting recipe, if one of the Autocrafters in the network receives a redstone signal, it crafts the object, which is then output from the bottom of whichever autocrafter recieved the signal. In this manner, you need less autocrafters to make simpler products- buttons, for example, would only need a single crafter. More complex recipes, however- such as an iron block- would require nine autocrafters in a 3*3 pattern.
Oven ~ A less expensive crafting block made using a Smoker, some redstone, and some iron. The Oven can be fed food type resources, and automatically cooks them. While slower than a smoker, it requires slightly less fuel input, and can be used to automate the production of cooked foods.
Cauldrons ~ Could be used to automate potion making. When potion ingredients are dumped into a cauldron, and said cauldron is also input blaze powder, (Which causes an orange bar on the side to fill up), it can brew potions without the aid of a player. Potions can then be drained from the bottom via a hopper supplied with empty bottles.
A Means of Crafting Spawners ~ This is kind of iffy- finding ways to establish a base around a spawner is already an interesting game mechanic. As such, a craftable mob spawner should require a Nether Star to craft- or perhaps just a lot of netherite. Then, a central ingredient could determine what type of spawner it is- (blaze powder for blazes, spider eyes for spiders, gunpowder for creepers, rotten flesh for zombies, etc.) This would only work with hostile mobs.
Redstone Wrench ~ This sort of goes without saying. A simple tool that can rotate a redstone device ninety degrees so you're not always worried about placing them.
Dispensers Can Plant Seeds & use Bonemeal ~ Exactly what the name implies.
Dispenser-Minecarts that Can Place Tracks ~ Also exactly what the name implies.
End Chests can be Fed by Hoppers ~ Once more, exactly what the name implies.
Iron & Netherite Drill ~ The Iron drill breaks blocks when pushed up against them by a piston- however, blocks broken with the iron drill are not dropped. As such, it's only really useful for tunnel boring. The Netherite drill, on the other hand, requires an End rod to craft. It can break blocks and drop things, allowing for automated cobblestone generators, tree farms, quarries, etc.
Spikes ~ I suggested this seperatly in another thread- but retractable spikes could be used both as a fun trap, (Well, I mean, traps aren't necessarily fun), and a means of making more efficient mob grinders. the damage taken on spikes depends on how far a fall you take on them- and a very high amount of damage is dealt if you're crushed by spikes.
Grates ~ Another mob grinder/farm thing, Grates allow items to fall through, but not entities. They're made with iron.
Trough ~ This is also shamelessly borrowed from Quark- feeding troughs can be supplied with food automatically, and mobs will eat from them- however, they have only about a fifty percent chance of inducing breeding mode when animals eat from them.