Ehhhhh, I don't agree here.
The collecting aspects in DKC2 come down to only three major elements - Banana Coins, Kremkoins and DK Coins. The former are purely an aside used for hints, repeat saves and backtracking, and usually you have enough of them to do what you need to do optimally. Kremkoins are the best kind of collectible you can get because they encourage you to scour the levels and beat the varied and fun bonus levels you get alongside them. They reward the player for being creative and crafty, and usually it's pretty easy to digest where they're going to be available when you account for all the gimmicks involved in accessing them. The reward that comes alongside them is also worth it. They do a great job in building up player investment and is pretty much how I feel a collectible bonus should be. The Kremkoins are undoubtedly part of the reason why DKC2 is so fondly remembered alongside it's predecessor and sequel. They were designed all around well managed secret areas that were fun, relatively difficult, yet fair to discover, and always had a fun little bonus to test yourself.
DK Coins are the only ones that seem a bit arbitrary and more hidden but they still effectively follow the same line of thinking as the Kremkoins and don't even really add onto anything in the game, those are really just for the dedicated players who want to fulfill a little endgame ranking.
In contrast, Yoshi's Island kind of just demands too much of the player in terms of maintaining their collectibles, having to "hide" several of them behind regular items and overall making most of the occurrences be circumstantial (you need things like Eggs for them a lot of the time which is never a guarantee for you to have) rather than any specific design choice that is solely dependent on your wit and ability to overcome the obstacles necessary. You need to play that game as surgery if you want the 100%. It's rarely about how you perceive the environment, and outside of that you always have to worry about getting screwed of those damn stars by the time you get to the boss or ending of the level.