That sounds awful tbh. Every fighter would look the same, like they're a cast of the latest season of TUF or sth.
On the plus side for those new to the sport or viewers who are unfamiliar with the two fighters in action it would be clear that 'this fighter' is in the blue apparel and the 'other fighter' is in the red apparel. Or whatever color scheme(s) get decided upon. It may seem like a small thing but when listening to color commentary if you can't figure out who is who it takes away from the experience. I think this is a positive all the way around, unless of course a fighter is forced to endorse a company they don't want to support.
Reading this thread it does seem that this can get more sticky. Nike is an interesting example as their record overseas of labour treatment is terrible. Would Jeff Monson (when he was in UFC) wear Nike? Given what I know about his outlook he would not. Would the Korean Zombie where Hayabusa given his feelings towards the rising sun logo? I understand they have since pulled that line, but it does show that this situation will need some finesse to get a level ground that works for a lot of different people.
I still see this as a positive financial move for lower card fighters and think it is a natural progression for both the sport and the UFC.