As far as collectibles go, amiibos are nice looking. For the Nintendo fan with extra cash, I can see having one or two amiibo of their favorite characters. The BotW Guardian amiibo is really nice, with opposable limbs. The squishy Metroid amiibo also sounds pretty cool. But introducing game functionality to these collectibles is when it starts being a slippery slope, especially because they can be extremely hard to find. And the more important content that is made exclusive to these things, the worse the problem becomes.