It factors because as long as the look isn't drastically changed and the characters are recognizable its fine. it just comes off as lazy. Tekken changing costumes every game was nice.
Technically, all they have to do to change costumes is to make the new 2P ones 1P and the 1P old "iconic" one 2P. But new costumes is not all I want. I want a new "LOOK." Military Hwoarang, Paul with hair parting in the middle, mature Xiaoyu. That's the type of art direction I want.
If you just want new costumes, then I'm sure each character will have those as their second/third options.