Those examples you names don’t have “horrendous quality”. They are also most certainly not ugly. I think they actually have tons of style and their aesthetics are quite consistent and straightforward. I also downloaded them and they all play fine.

I’m a bit baffled why you consider them to be so horrible …

They aren’t beautiful, they aren’t complex and they are derivative. 2048 is a disgrace, obviously, but those apps are fine.

I think Apple steers away from rejecting games because there just aren’t HIGs for those. So you can’t reject them based on those, and also not really their aesthetics. Games are explicitly allowed to have aesthetics and even UI elements different from other apps because of their very nature. They are tricky territory.