I feel like it's pretty shitty to excuse something like this, whether you see it as QoL or a cheat code.
And what would expect the amiibo to do? I'd much rather it be something pointless like this than locking major content like it was in Twilight Princess. Amiibo are a bad thing in general, but you can't really expect Nintendo to stop making them, and they will always put some kind of in-game use for them since that's (supposedly) the whole appeal of the concept.
I feel this is the exact opposite of something pointless, though. Whether you feel it's a needless cheat code or not, it's a feature. It's not actually that different from Twilight Princesses feature being locked behind amiibo, other then that was a bigger feature being locked behind amiibo. The most pointless amiibo inclusions are when you just get something like an easily-accessible collectible in game through scanning an amiibo, like the ones where you can only scan an amiibo once or twice a day to stop farming of things you can already easily farm in game, which is usually the most pro-consumer ones because you don't need to buy an amiibo to access that content. It's not a feature that you otherwise wouldn't have. It's just something regularly in the game.