I think for some people it is getting old, and the changes are giving them an excuse to back out. But some have also seen changes stack on top of changes - and eventually, they don't have what they originally thought they'd bought.
For us, a big one is dining - doesn't have anything to do with DVC, but it is a factor in "will we keep our points." When we made "the Disney committment" we felt WDW had a wide variety of pretty decent restaurants. We still needed to make reservations for them, but we generally got what we wanted calling only a few weeks out. I figured we were likely to own DVC for a long time - we'd transition to golf and dinner once the kids outgrew parks. Over the past few years, dining has gotten more standardized, more expensive on cash, more crowded with the DDP, and the quality has not improved - it isn't ENJOYABLE anymore. NOW, because of the dining situation, I really don't want to golf Disney. If we stack that on top of more crowds, longer lines, aging children - Disney becomes a place I wouldn't make a committment to TODAY - but it hasn't gotten to the point where I'm ready to file for divorce or even seperate, but at this point we are together more for the kids.