If Rare didn't insanely exaggerate the collectathon thing before DK64, it's definitely the game that completely fucking jumped the shark. It has as many kinds of collectables as other games has collectables in total. The Banjo games on 64 are good, but they pushed it a bit far, too.

Fun fact: DK64 is broken and was published that way. It contains a memory leak they couldn't get rid of in time, which'll eventually cause the game to crash. It requires the RAM expansion doohickey - not because it's an engine requirement or for textures, like Majora's Mask, but to stall the inevitable crash.