The Meaning of Life, the Universe, and Everything.
Camels being the same/having the same uses as llamas doesn't make much sense, seeing as people very rarely use llamas anyway. You'd be adding in a mob that's a carbon copy of an already redundant mob.
Snakes and scorpions are both ideas I like, but you'd need to make them uncommon or nerf their special properties massively on easy difficulty. Snake-skin could maybe be added as a drop, for upgrading leather armour into something only slightly worse than iron(seeing as most people skip leather completely, added incentive). For scorpions they could drop their tails for use as arrowheads, a wither arrow would be pretty powerful but by having them drop from an uncommon mob with a less than 100% chance + only a 1:1 ratio for crafting could balance them out.
I'm not sure why a dry desert would have sandstone instead of sand, sandstone isn't any drier than sand. It's literally just compressed sand. It would make more sense for the dry deserts to have no cacti or dead shrubs, and with a reduced chance to spawn with a river running through it.
Oasis would be a completely different biome just based on design. You'd need to make it a mini-biome, already been suggested a number of times but something i'd like to see.
Sand spikes as a biome 1) makes no sense as the sand would just be blown over and 2) is rather unimaginative + is a carbon copy of an existing biome but with a block and theme change.
The mirage system is interesting but would discourage people from exploring or settling in deserts, which is the opposite of what you want without putting some rather tantalising new resources in as a reward for persevering.
One obvious desert type that you missed out on is the red sand desert, as in the red sand from mesas. Having a low chance to have a desert spawn as a red sand desert would be quite the find, especially considering the limited availability of red sand compared to regular sand or even terracotta.
Partial support, but really only because I agree that deserts need work (just like almost every other biome).
Ohhhh... Desert. I thought this post was about crafting desserts. Mmmmm, dessert...
About deserts, I think an 'oasis' biome could simply be a small piece of a 'river' biome generated in an isolated part of a big desert. That would make a perfect oasis in the middle of a desert, since there'd be some green grass and trees with a pool of water (instead of the brown-ish grass that you'd normally see in a desert or savanna biome).
Also, since there's a 'bryce' biome for mesas, I think there should be a 'sonora' biome for deserts. Then a new plant could be created that would be made up of cactus blocks in the shape of a saguaro cactus (the classic cactus with the arms) or a joshua tree (looks like a yucca plant that's a tree). That cactus could be a plant that grows similar to a chorus plant, except it's made of cactus blocks. That would also allow recycling code (use the 'chorus plant' algorithm to generate the 'saguaro cactus' plant), instead of creating something new completely from scratch. Also could combine your idea of 'dry desert' with a desert floor made of sandstone.
Camels would be cool too, maybe make them spawn close to oasis areas and they can be ridden with carpets (similar to llamas), can have crates put on them (similar to donkeys), and can be controlled like horses.
More plants in the desert would be nice too. Occasional 'grass' in the sand, the cacti ideas I previously provided, and prickly pear cactus that can be cooked and used as a food source.
Dessert are preety deadly places in real life but in minecraft they are nothing really to be afraid of. Here are some changes that could make the dessert not only more deadly but interesting. I think desserts are pretty nice and tasty things. My favorite is ice cream.Okay I'll stop with the joke.
-The dessert update (1.15 or something)
Camels: maybe you could use them like llamas Camels could be interesting, but there would have to be a reason to use them. Maybe horses get tired from the heat in the desert so it is better to use a camel. Remember: All features should have a purpose (other than just being there).
Snakes: they poison you when they attack you What would these look like? A cool item that could be found in desert temples could be a snake flute that can sort of controls snakes.
Scorpions: same as snakes but with wither I personally think scorpions should be more like spiders. Also, why would they give the player wither? Isn't the wither effect only something found in the Nether?
Dry dessert: floor is out of sandstone This would be a little weird, so I don't know about this one.
Oasis This would be awesome.
Sand spikes: like ice spikes but out of sand This is a really cool idea!
After staying in the dessert for a long time you will start seeing mirages of fake animals: this one should be pretty easy to imploment because the illusioner already kinda does that As long as it isn't too laggy, this would be really neat and interesting.
Also when I read the title I thought you were talking about cakes.
I like camels, but if they're just like llama's there's really no point of them. Maybe if they were ridable and/or could carry more chests.
Snakes, now that idea I like. I can't imagine what they'd look like though. I'd like to see these kind of dangerous animals.
Scorpions, I'm not sure about the wither effect, but I like them too. Perhaps they could be a desert-versions of spiders (like how husks are with zombies)
Oasis sounds alright, I imagine they'd be rare in deserts.
And the mirage idea is actually interesting, maybe it'd be a little annoying though.
The Meaning of Life, the Universe, and Everything.
Camels should be just an alternative version of a llama that spawns in deserts. Just like Donkeys and Horses, or Husks and Zombies.
Scorpions, as a desert alternative/bonus to spiders in the way that husks are to zombies. Would also be affected by Bane of Arthropods enchantment, which is currently only useful against just spiders, while smite affects basically everything that's not a spider.
Deserts already have too much water in them. An oasis would only be necessary if lakes and rivers didn't generate inside deserts.
It seems that everyone think that scorpions should just be reskined spiders. I’m actually not a fan of this. I think that scorpions that give a player the wither effect is a good idea. Just as long as they aren’t spawning left and right. They should be a rare mob.