So Minecraft is at it's best when it's just a flat plane in which you can walk around, and mobs walk toward you? Oh and you can jump and gravtiy will pull you back down.
Apparently you don't need anything else to make a good game, it's all just unnecessary fluff.
One of the Classic versions is exactly that, except that the only mobs around move randomly.
And playing it quickly shows why the latter versions are clearly superior or, in other words, your argument practically references (Althrough it may not be intentional) one early version AND points out why it wasn't fun.
Physics are necessary. Controls are necessary. Mob AI is necessary.
And all 3 things already existed back then. In fact, physics didn't change much since Infdev, apart from the addition of Redstone and fluids; while it's obvious that there were already controls, considering that people already played those versions. Finally, mob AI already existed back then, even if it was so simple that the mobs back then would make current Villagers look intelligent in comparison.
Almost all of those actually are very unnecessary. Maybe a few of them are worthwhile changes, but calling them "necessary" implies the game is lost without them. They are just icing, not eggs or milk.
At what point is something "necessary"? Up to an extent, it could be argued that every update after Classic or probably Infdev was unnecessary, and up until then, the changes were needed to make a playable game.
1.7/1.8 will be the greatest unless in 1.13/1.14 will have the "normal" PvP
Please, no. Combat doesn't need to be "Click the LMB a lot to become untouchable) again just because of a few "PvP pros" that are actually awful at gaming and are useless at tactics, using bows, teamwork, or even any combat more complex than "I move and left-click".
Why? Is it a bad thing that they a.) added unfinished features, or b.) bad that they didn't finish them? If a, use an older version of the game, if b, wait for the features to be finished in later updates. I don't see a need for polar bears to have drops, nobody is forcing you to kill them. I also don't see a need for iron ingots to have more uses yet, they are currently making future uses possible because they exist. If you're bothered about the development resource expenditure, I can understand for polar bears though I personally appreciate getting more ambient mob types because the same three passive mobs was getting a little stale, but I doubt iron ingots took any significant amount of development effort.
The issue is that those features aren't developed enough, even through they were first added in snapshots, they hardly changed or added to them before they were added.
Polar Bears DO need drops. They have more health than most common Overworld hostile mobs, deal more damage, and have an unique behavior. They're not mere "ambient mobs". If they were, they would have no drops, be passive, and have low health (As is the case with Bats). Right now, their only notable feature is that they indirectly make the biomes they spawn in safer because they can also attack hostile mobs, but apart from that, they seem to need completion.
I guess you've had a braincramp (I'm NOT mocking you with this, as this kind of awkward mistakes is pretty common), but I never said that iron ingots were useless.
Finally, it's also true that1.13 or later versions will likely expand on those items, considering that a similar argument could have been used against Shulkers, which also were initially released without drops, but now they have drops that are easily a better reason to seek out End Cities than obtaining the Elytra.
Creepers do not have any unique drops either; do you think they don't add content either? Or if talking about just friendly mobs, there's parrots, bats, mooshroom, sheep, llama, horse...and more.
Iron (ingot, and therefore nugget) is already renewable, from golems.
So what point are you trying to make? You want them to add more, but not polar bears?
Creepers used to be the only mobs that dropped Gunpowder, and still are the most reliable source, as Witches are less common and has a lot of other drops, so they're less likely to drop Gunpowder, while Ghasts are an awful source of Gunpowder because their drops can fall into lava or fire (Or somewhere that is difficult to reach) and are more difficult to kill.
Gold Nuggets are used to make a Firework Star effect, Golden Carrots and Glistering Melons, so they have a purpose in that they have other uses apart from crafting them into Gold Ingots. Gold Nuggets also they provide another source of gold because they can be dropped by Zombie Pigmen and found in Igloos.
Iron Nuggets are only used to make Iron Ingots, and are only found by either crafting them from iron ingots (Which is pointless, unlike Gold Nuggets, due to their lack of other uses) or by smelting iron tools and gear, which is only useful if it's an item you found and you're unwilling to craft (Which means that you're unlikely to obtain more of it), as it's more efficient to just keep near-broken Iron items and use them to repair other damaged gear, specially if the near-broken gear isn't enchanted, since then craft-repairing also provides bonus durability, so a few damaged tools can be turned into 1 near-new tool. Practically the ONLY exception to this is Chain Armor, which is worse than Iron armor anyways, but also requires iron ingots to repair, and generally falls into the "Item you're unwilling to make that was found by other means, such as mob drops" category (Except that you have to replace "make" with "trade for").
My point is that these two features seem unfinished. As if they should only be in a snapshot-only version and more features related to them were planned; and that Mojang should add more content that also has more depth, and should also give more depth to these two features, as they're apparently unfinished, as Iron Nuggets are, as pointed out above, nearly pointless as they currently are, while Polar Bears have no unique drops, of which they're not even a good source of (Both fishing and Guardian grinding are better, as the former is safer, and both also provide other items).
If anything, they don't add enough content, as evidenced by Polar Bears (Who have no unique drops), or Iron Nuggets (Which are only used to craft Iron Ingots, unlike Gold Nuggets; and which are also only obtained by smelting iron tools, unlike Gold Nuggets, which also drop from Zombie Pigmen, so they're also a source of renewable gold).