The thing with the Amiibo is that they can be used on multiple games across multiple systems. This is why you're incorrect @Sheikah.
The Amiibo isn't Day 1 DLC, it's simply a key. Splatoon has Day 1 DLC, correct, but Amiibo is not that DLC because it can be used with other games too to unlock other DLC, so in this respect Amiibo is fantastic value.
Calling out Nintendo for making the Splatoon DLC Day 1 DLC is fair enough I agree, but to call out the Amiibo as being Day 1 DLC is incorrect as it's much more than that.
Still, I do think they should offer the DLC separately to being unlocked by Amiibo in their games.