The famous PCEngine Castlevania is a typical old-school platformer, that, like the third NES Castlevania, offers different routes through the game. I prefer the more linear gameplay of the SNES/Genesis Castlevanias.
It’s not that I dislike non-linearity in games, but the connected level architecture of the later platformer/RPG-hybrid Castlevanias is much more suited to backtracking and exploring alternative routes than a platformer where everything is cut up into little, disconnected levels. There’s just no easy way to go back or chose a level, which makes trying out the alternative routes a pain in the butt.
This annoyance is purely a matter of game design on a meta-level, the varied stages and bosses are really fun to beat and from that angle the game is quite good, but I would have preferred to get all that in one playthrough without the need to try out different routes.