My son said, "I dont want to go on vacation to stand in line, that is not fun" Seriously, Disney is not a vacation, you need a vacation after that vacation....LOL
Today's kids are a lot smarter than many parents give them credit for. They know the value of standing in line not being fun -- plus, a vacation is doing what the vacationer wants to do, on the vacationer's terms.
I think a lot of what motivated the original post on this thread is television advertising/marketing -- Universal Orlando, for example, is amped-up with characters such as Spider-Man and Shrek. Even without shuttle launches, Kennedy Space Center comes-across as way cool for the science-minded. Meanwhile Disney is...well, Disney - complete with Princesses and Fairies!
Add to that the "overload" of Princesses and Fairies that has been taking place at the MK over the past couple of years (at the expense of gender-neutral attractions such as "Mickey's Toontown Fair"), and you might get the idea of where the young men in your household are coming-from in their reluctance to go to the "happiest place on earth".
In Disney's defense, they could do a better job at marketing "what's cool" about their parks/resorts -- many people, particuarly those who've never been there, think it's a kiddie park with Mickey and friends.