I can probably step on the toes of both sides on this one. I don't feel left out, I see the big picture. If they were just giving away the free dining without other requirements, that'd be MUCH different. I can actually get the free dining if I want by staying on cash and for some situations it might be a better deal.
DVC doesn't actually disclose how much they hold back but they do disclose a generalization of how much they will likely hold back. This is a business, certainly, and DVD/DVC are in business to make money. They do have certain legal and ethical obligations, some of which are noted in this thread. I feel it is in their best interest in the long run to keep the members happy as much as possible (some would say if possible even impossible), I'm not saying they should wine & dine just that they keep cutting little things here and there (DVC and Disney both) and that it adds up and that includes, IMO, the areas that they are contractually obligated. The membership as a whole do not seem NEARLY as satisfied to me as even 5-7 years ago and it's not just higher expectations IMO.
The points DVC holds back are primarily intended as a buffer for Maint and other issues. My info is that they don't normally use those points for rental though they do at times. Certainly every unit has a "cost", even if that cost is in terms of maint fees, taxes and lost income because they didn't sell it. Though do have other units they rent out including unsold inventory, repurchased inventory, those from points exchanged for
DCL and the like for DVD and Breakage inventory for DVC.