Certainly not trying to speak for all DVC'ers, I just think that the situation you describe is a relatively small subset of DVC'ers. I would imagine that if you compared demand for concierge vs. non-concierge services at non-DVC resorts that percentage would end up being notably smaller if you made concierge available across all DVC.
I for one could see myself in the same situation as you describe, springing for the "extras" of Reunion Station for that one special trip, such as an anniversary or special birthday. But as for those types of situations sustaining the Reunion Station model when DVC itself is marketed toward returning families (rather than the once-in-a-lifetime vacationers), I could see this failing from the outset.