In DKC, you need to fall into a pit to find a secret. I think there's some minor hint of a barrel's existence there, but that is a thing you have to do in that game.
Yoshi's Island, on the other hand, is everything right in a platformer, though I agree with whoever made the comment about having to collect everything. I love YI, but replaying it can become torturous because I am compelled to collect everything.