Why does everyone hate Unity (the game engine)? I've used it and it's honestly not that bad.

Good question.. However I prefer UnrealEngine over it. :)

I'm developing crysis 4 with cryengine 4

Anything that lowers the barrier for entry into a field gets a bad rep.
Usually the tool is just fine, but it allows less-skilled programmers to participate --which allows their subpar products into the market.
Suddenly you see a bunch of garbage produced with that tool and folks start saying the tool produces garbage.

Mostly because of the many trash game made with it. But after one jeahr as a game dev student I need to say that I don't like it that much because everything is working fine on the front but as soon as you start using the more uncommon parts of unity(Android) you get buggs witch can only be fixed by using debricated Android sdk versions. So in my opinion it's a good engine to start gameplay programming and if you want do do more advanst stuff you need to accept some inconveniences and hary implemtations.

because people think it's easier than unreal because it has simpler ui so more amateurs pick it up and when they figure out they can't code for shit, they release crap shit and hate on the engine. also because crap devs who expect the engine to enforce some structure on them instead of making their own structure are diaappoint. also because they can't be bothered to watch two talks explaining why their performance is shit when they call Camera.main in Update() of 30 scripts instead of caching it, and some similar shit. simply - it looks simple so people assume it's for amateurs, and they are then all angry when their amateurish attempts are hard to make and look, feel and run like shit