Well, with people running any colour of marine as any chapter, folks who want the best 'bang for the buck', will not be too concerned by what their models look like.
Hobbyists will for sure be keen to theme their army on a certain regiment (like always), but for tournament play, I can't see that happening.
But, we'll see. It'd be nice to be rewarded for putting the effort in. I do like the opportunity the traits do allow for building your own custom regiments, and building a cool army around a certain set of traits.
Also, once all the armies have their own books with their own 'traits', then things will be on an even footing. For example, Marines and Chaos each have a chapter/legion which gives their opponents a -1 to hit modifier beyond 12". Shooting twice (or whatever), doesn't help as much if you're not moving closer and then always hitting on 5's (or worse).
People's terrain should also not allow clear line of fire across the whole table.