The thing is that nothing is guaranteed. Look at some of the threads on DIS and you have drunk people, chair hogging, some service problems (grant it very rare), food being hit-or-miss sometimes, childcare issues, etc. Is it less likely? Probably.
I suppose that with Disney having 4 ships, and the other lines having many, many more ships, you're more likely to hear of problems on the other lines just because of the probability being higher by a higher passenger count. Disney, of course, is a leader in service-related things - that's why they charge what they do and why they have that reputation. You walk into a Disney ship expecting to be well taken care of and that things will be done right or get fixed right away if possible. That's great and all, but you have to think that other lines wouldn't be able to maintain customer loyalty at all if they were indeed THAT bad.
Magical worlds are fantastic for little ones. We're just about out of that need, and more into the "we want to have fun!" active lifestyle, so perhaps for us we don't have that pressing need. I'm sure at the right price/sale we *might* go DCL in the future, but for now, I don't see it. Heck, $30,000-$40,000 would pay for nearly all 4 years of college that my DD wants to go to. I could really set her up with a great future with no student loans weighing her down.
Unfortunately, families have to think like that. And I think that's something Disney is forgetting. If you look at the Destination America special, it talks about how Walt Disney wanted to make a place where all families could come and enjoy the place as a family, enjoy something special and magical as a family. They are starting to miss the part where it was supposed to be "all" families, not just the wealthy.