I have NFC tags and an android phone, so it wasn't because I couldn't access the content, it was a decision based on principle. I had thought to buy the game and support 2D Metroids without bothering with the amiibo, but refusing to buy the amiibo alone while still buying the base game wouldn't have sent any sort of message. The act of sectioning off content for DLC (minus, of course, the obvious costs of manufacture and shipping which came in this specific instance of the DLC being part of an amiibo) doesn't have any overhead, so whether I bought a "full" game for $40 or whether I bought "most" of the game for $40 and forewent the amiibo, Nintendo would still get my $40 and would see no loss aside from, as mentioned, the costs of manufacturing and shipping the amiibo. Nintendo would hypothetically see an immediate loss from a lost amiibo sale for this case, but the only message that would have sent is that they shouldn't tie DLC to amiibo, and instead have it for sale digitally, which I can only imagine has literally zero overhead in terms of monetary costs and means they would not lose any money. The only way I'd send a message that I didn't appreciate this kind of practice was by not buying the game at all, which was unfortunate, as I also wanted to send the message that I want more 2D Metroid games.
So what I mean to say is that I'm sure it was all sorts of rad as a game, but to me, being even an incredibly minuscule part of making a statement on DLC models/practices was more important than experiencing a game I thought I'd really enjoy.
Ah, and also understand that I'm merely explaining my reasoning behind doing what I did and not trying to push morals or responsibility onto anyone else. I don't mean to be a crusader, only to elucidate.