If there are collectibles, i will collect them... trying to get 10 coins each match to get all the gear. Finished 100cc in a few hours with at least 2 stars on every circuit. The 3D doesn't bother me that much on this, compared to Zelda/Starfox.
I only bought it because there's no update on the Crown3ds yet :<
There are collectibles. There are a looooot of collectibles. I don't think I'm ever going to get them all unless I play online a lot more. After a while, getting new parts for your kart take a lot more coins than the first couple did.