Rev,i think you under estimate the determination some people have. when ever a game lets a community create it's own stuff, there are always people who create good stuff for free even if it's hard, time consuming, etc. look at LBP, Halo forge, the sims, minecraft, etc.
I think I don't; after all this is one of the ways how people get into the whole business of making games.
But I can see a lot of people making what
they want, not what the game needs. And then whine about their creations being rejected because they're too Sci-Fi- or Fantasy-esque.
it does seem like a perfect fit to me given how customisable brink is by nature.
That is also the weak point.
TF2 hats and weapons are a lot less complex than clothing items in BRINK. You basicly need access to all the other models so your creations do not interfere with the others (to avoid clipping errors for example).
If you're really dedicated to the whole modelling thing and create something you consider well worthy to be put into BRINK, you can always just contact the devs (on the twitters, for example) and ask for their opinion about your creation.