I played both in my childhood, and I don’t think I’ve ever returned to Tooie after I beat it first time. It’s a good game, but doesn’t have that same lasting appeal as the first game.
You touched a bit on the why: the game is too ambitious. The levels are too massive and too intertwined. Smaller isolated levels fit the collectathon format better.
I remember having lots of fun with the multiplayer though, so that’s a bonus.
If you want to continue the collectathon journey you should try out Donkey Kong 64. It’s also a game that falls under its own ambitions, but in different ways. Still a good game, but nothing beats Kazooie.
DK64 is sometimes accused of killing the collectathon genre. While I’m not sure if the accusations are deserved, DK64 was too ambitious with the amount of collectibles and the size of levels for its own good.
It’s still a great game. I think I prefer DK64 over Tooie overall.