I just don't think Nintendo had their priorities straight when it came to using amiibos in Smash Bros in particular. The whole selling point of amiibos in Smash was that they would learn and adopt new strategies as they continued to play, and would eventually beat everyone by outsmarting them. Actually being a challenge, partially by cheating, was never the main goal AFAIK, and the fact that they cheat with higher damage and weight really downplays the learning aspect, defeating the purpose of the amiibo in the first place.
Nintendo, if you're reading this, take the stat buffs off of uncustomized amiibos. Keep the option to feed equipment - that's fine - but don't make the untouched amiibos blatant cheaters like they are now.