The appeal for Amiibo, to me, at least, is that I can utilize them across a number of games I already own, which cuts the price of my Link Amiibo down to roughly "three dollars or DLC per game" with that number most likely shrinking as Zelda, Splatoon, and other titles being released down the line.
I like action figures. I own all the Nintendo Figma and I love them very much. They're nice display pieces for fans and they have in-game functionality. I was on the fence about picking up Mario, but damn, that pose is just too cool to pass up.
That being said, there's no way this is a "collect them all" type of thing for me, and anyone who does feel that way is pretty strange, in my opinion. Judging by what is being released for Smash Bros. you can get a pretty good idea of what sort of games will get Amiibo support in the future, and that's okay with me.
Amiibos also can only have the data from one game written to them, but they can be read by many games, which is what happens in the case of Mario Kart and Hyrule Warriors. So these things do have multiple uses.