In my case, I just didn't dig the controls. Shrug.
Hollow Knight I've not checked out mainly because I don't like the look of the artstyle. Superficial, I know. But like I said, I loved Dead Cells - which I think is sort of similar gameplay-wise.
Shovel Knight is a solid example of a really good recent indie game. I guess ultimately, I think there's a TON of games coming out of the indie space right now. And some I think are great, and others I don't. But there's definitely some that get uber-hyped by gaming press that I don't really "get." On the flip, some are games I've loved and only discovered because of said uber-hype.