Oh, I agree. Kirby 1, 2 and Adventure are all amazing games in their own right. Super Star is one of the best Kirby games hands down, with Ultra being an excellent version in it's own right. I remember really liking the OST for Pinball and Block Ball. Dream Course and Canvass Curse I've yet to have a chance to play.
Amazing Mirror, Nightmare in Dreamland and Squeak Squad were all disappointments in my eyes.
Whatever it was, it was probably the same thing that happened in between Kirby Super Star and Kirby's Dreamland 3.