I rarely care about collectibles, but I appreciate it when they give you some kind of reward other than 15G.
Infamous did a decent job with the blast shards, where you became more powerful the more you collected. 350 might have been a little excessive though, especially when you have 2 left and no clue where to look.
Also, been playing Sly Collection, and the bottles gives you new moves if you find all of them in any given level.
As long as there is incentive I have no problem, but 100 feathers for a goddamn cape? F-U AssCreed.