<font face="times" size="+0">the primary reason for me is nostalgia/sentiment.
my family had wonderful family vacations at WDW when i was a kid. so, when i returned as an adult, it was great to "relive" those memories.
as an adult, i came to respect and enjoy WDW's attention to detail (i.e. Disney "Magic"), great customer service, great upkeep.
that lasted maybe about one trip. everything after that has been going downhill slowly, but i keep going back now because i keep giving WDW the benefit of the doubt. and also, if i'm being <i>truly</i> honest, i do "deceive" myself... after all, "Magic is about deception."

and i'm able to pretend things are still just as good... ignore all the declining things about WDW, and try to have a good time anyway. (sorry, i'm in a bitter mood today... )
anyway, the point is, i keep going back to try to recreate that same magical trip i had the first time i went as an adult. and each time has been close, but not quite. but the fact that it's close is often good enough, and i just settle for that. the big problem with settling for mediocrity is that Disney has figured out that people will settle, so that's probably why things have gone downhill. *sigh* at some point, we need to protest. but many of us value WDW vacations too much, that it's just way too hard to cut yourself off completely! so then Disney wins.
also, the second major reason i keep going back is the comfort level. because i've gone to WDW on vacation so many times, it's like going "home". which eventually leads to why we bought
DVC: so we can go "home" often. because people grow attached to their homes, and we (or at least i) grew attached to WDW. so, even if your neighborhood changes, and isn't as good as it used to be, it's still your home, and you're still attached to it. *sigh* </font>