I'm actually very familiar with their history and know about this. It doesn't excuse it, why bring it back now? Blue Mary completely loses her shirt when she's knocked into water in Real Bout Fatal Fury, but I can't imagine them every trying to pull that again. It's not a big deal, but it goes against the rest of how they treat that character and comes off as a cheap attempt to please certain audiences.
It's just something fun for the fans of the old games, I don't see anything wrong with it. It happens to only King and Yuri, both are from Art of Fighting.
SNK went the extra mile in XIII in a lot of ways, Yuri for example has two versions of her sprite. One with short hair and one with a pony tail. In a 2D game.
They even gave Kyo his classic look from KOF94, which must have been quite a bit of extra work.