So it started with DKC3? Huh. Doesn't sound like they are essential, even in that game. Completionist "increment a number" and "unlock a secret level" seems fine to me. That's why I'm so confused. I never finished any of the DKC SNES games, but I never ran into a progression wall (besides my own disinterest).
So long as the games structure doesn't revolve around collecting stuff, I don't think it's fair to write them off as collectathons.