I agree that this UFO lock is a terrible practice if not the worst scenario of amiibo. Namely because as you said not only does the amiibo lock content from previous games in the franchise, its locked behind a brand new Kirby amiibo when there is already one out. I don't know what justifies it in Nintendo/devs eyes. Maybe its because the level design doesn't really give way to have a UFO enemy, but I find it somewhat hard to believe that's the case as the game starts off against a giant UFO.
I can't however, cosign on he notion that they are the worst thing to happen this generation. This instance is just one of the worst case scenarios. There are better implementations that make much more sense. The Smash Kirby amiibo for example, is something I find to be pretty good implementation in this game.
Side note: I don't get the comments that justify amiibo like its good by saying its making the company money, or its going to say stay whether you like, or not so choose to buy it whether you like it or not, or even wait for the game to drop in price (especially ones like this because I think you are forgetting which company this is). This are a handful of reasons we call out other companies atrocious behavior such as micro-transactions and absurd levels of DLC, etc. There a better arguments and these are pretty bad.
