Other games will use the same amiibos as well, which multiplies the value depending on the amount of games they'll work in. Also, other games will use it differently. Perhaps others will make them mandatory ala Disney Infinity/skylanders.
I'm really not a fan of the Skylanders and Disney Infinity things and this is the same thing so I'll pass on it. Just seems like an unnecessary gimmick to me and one that I can't see myself spending money on.