And aren't you buying the game for the game? Do you really need the extras? Like, if none of the other stuff existed, would you care?
I prefer extras that are unlocked by gaming skill and accomplishments rather than just paying to get an extra. I look to F-Zero GX as the best example of this. There were characters/racers, karts/parts, and other tracks/cups that you could unlock by basically getting good. There were further little extras like different questions and responses you could get from a racer when you ask them a question at the end of the race depending on the difficulty giving you more of a reason to play as them all. If you could beat any Master cup with a racer then you got a short goofy video of that racer. None of that was needed to enjoy the game but it provided a nice carrot/stick incentive for those that did achieve such feats.
Now, if it was a case where an extra character, the hardest difficulty or unlocking racer videos was hidden behind an Amiibo, sure, I can still play the game and have a good time but the experience would be diminished. Of course, I know it would be diminished having played and seen such extras but that would be the difference between myself and someone else who played without those extras. What happens if I really liked that F-Zero game with all the extra Amiibo content but others found the game so-so without it? I could be in the minority opinion from that disconnect. If the majority opinion is then tepid or negative then will it have an effect on another F-Zero game being made? Amiibo could do some harm in this regard.
So far, Nintendo has kept Amiibo from really changing the most common experiences possible in a game. Having played some games with Amiibo support but not owning the Amiibo hasn't made much difference between my experience and someone who has the Amiibo. Let's use BotW as an example. That is a game that can have many different experiences for a player. Amiibo had a minor effect on the experience. They just offer some extra outfits that are tied specifically to them. You can also get some free materials which may make it easier to acquire upgrades or rupees faster than normal. Sure, Epona is tied to Amiibo but there are other horses out there with better stats anyways so none of that really has a large enough factor to cause Amiibo owners a better experience than a player without. Yet, perhaps as my nature of play to accomplish and complete everything, it bugs me to know that these extra costumes and "true" Epona are something I can't acquire in my game. Most likely, I'd hardly use them and they'd just be in my inventory as a way of proving/satisfying my desire to 100% complete something. Just knowing those things are out there but I can't acquire them irritates me. If it was a case like F-Zero GX where I had to complete a Master cup to unlock something and I didn't bother then I'd be ok with that. That's on me to get done. With stuff blocked by Amiibo that isn't from me not accomplishing something, that's me being blocked out by a decision to try and squeeze more money out of me for wanting to play the game.
If none of the other stuff existed, would I care? No. Stuff doesn't in other games but I still speculate about what could be added to it for a sequel or what may have helped make it better but that game is what it is and I accept it for the completed title that it is. With Amiibo, I know other stuff exists so now I do care about it because it is actual content in the game that is being blocked unlike a game released without such stuff so there is nothing being blocked in it. Yes, going back to BotW, I'm buying and playing the game for the game and experience it offers. Yet, with even how good that game is, I still have this twinge of disappointment when reviewing my armor of knowing I don't have all the armor possible because of Amiibo. As stupid as it is there is some kind of psychology at play and I'm not sure what the solution is.
There's other future Amiibo related issues I could go into but I've typed enough so I'll let you all disseminate this bit of ranting and raving and attack me as you see fit on it.