It's on-disc DLC except instead of being tied to a storefront of uncertain longetivity, it's tied to expensive plastic crap of slightly less uncertain longevity that are impossible to get. I don't like Amiibos.
That being said, the appeal is obvious: Not too shitty figures of beloved characters (most who never get merchandise otherwise) + scarcity driving up speculators = $$$
Nah, they're not for me, either. Granted, I do like to buy Mario figures sometimes, even better if they're at a seaside arcade or something as prizes, as has been the case a few times before, but Amiibos just seem like a waste of time. They're pretty much just e-Reader cards with a plastic shell. Even the figures themselves are in a distinct pose, so they don't really function as toys, either. I dunno, man.