Teasing aside, the timing is the biggest issue.
Announcing it before the game even releases, even if the content isn't actually made yet, just feels fucked up given how long they've had to work on the game, and how many times it was delayed.
Announcing the DLC now is like dangling a second carrot in front of the donkey before it ever got to eat the first. (i.e. taking the piss)
In second place is how rushed some of the content actually is, the shirt for example just feels like nothing but padding, the same shit you see retailers pulling when they offer exclusive skin dlc for preordering with them, in joint second place is the high probability that since the launch window is pretty anemic, a lot of people are going to buy this thing out of literally having nothing else to play, and that will only bolster Nintendo's future plans to continue to pull this kinda thing with future games, something they have done very rarely in the past.
I dislike DLC at the best of times but DLC announced before a games even out... yeah you can fuck right off.
