It's not about making them "as drab as possible" it's just about avoiding the ridiculous, sexist, overly revealing costumes that a lot of those kind of games have.To me..
It's the shift to do something before there's a potential or likely a nonexistant problem.
Make a main female character as drab as possible so not to offend Twitter mob, or whomever would be offended by a sexy girl or guy. But be proactive before anybody says a thing. And take it to a degree that is way to far.
As said.. A sexy game character, have there costume modified to not offend the "westren" audience. They don't want to be pinged by some Twitter karen .. So they change it.
Some people are just getting tired of the women constantly running around 9/10 naked, while the men are also fully clothed. There is nothing wrong with showing some skin, but some of those games take it to a ridiculous extreme.