My opinion: platformers are great when player doesn't have double jump nor coyote time. This not only forces player to be more careful and think before jumping but also forces developers or at least level designers to design platforms, walls, traps etc properly. The goal is to ensure player can jump from platform to platform (if it's intended to be) safely while keeping the challenge.
I'm getting sick with platformers giving double jump and coyote time as default features.
Depends.
If it's a precision platformer or a platformer with wonky physics, then Coyote Time is usually a positive thing to have otherwise the dude playing runs off into every pit.
Most recent example of that is from one of Vinesauce's streams, he struggled to get 1 of the collectibles because he would always run off the higher platforms because it's a janky platformer with Unity's default physics or something like that. (At 17:42)
Most indie games that use air jumps aren't fast-paced platformers nor even precision platformers, they're traditional platformers like SMB. So I agree in spirit that the inclusion of a double jump is only making those games way worse.
I think the problem more likely comes in when these features are added after a level or challenge is designed in order to make the experience easier. As with any mechanic, it is possible to make difficult levels or challenges based around double-jumping or including coyote time. The window for error just has to be adjusted to account for these things instead of just designing the challenges as if those features weren't there.
