Hmm - I'll have to check out the Great Chasm proposal - I think that was slightly before my time.
In that case, DC, I feel like that's what we're already doing, no? HM's Horselords of the Pell, for instance, suggests a fluff that characters with certain abilities would gravitate towards. By creating fluff, we're already creating cultures which suggest certain tie-ins to the mechanics.
I'm not trying to be snarky - I feel like we're already doing what you're suggesting (at least as I understand it), if in a disorderly and ad hoc way (which probably can't be helped).
I suppose I just prefer more order than chaos in my RPG's, but I suppose a tad bit of chaos can't be helped