I hate flip-flops while in the parks or restaurants. At a pool, beach, water park, fine. Even at a hotel, fine. You might be on the way to the pool.
Yeah, they might be comfortable, but they are really pushing the line too close to being barefoot. That, and the sound they make. Man-o-man!
I have no problem with open-toed shoes. If you can look at your own feet and say "Yeah, people should stare at my very nice toes while in line" in complete confidence, then fine. By all means put on open toed anything, (except flip flops) and go to town.
If, on the other hand, anyone has ever suggested or it has entered your mind at all that you should not wear open toe anything on those nasty foot claws of yours, please do the rest of the world a favor and cover 'em up when out in public besides the places mentioned above as OK.
What's wrong with sandals if you want open and airy? Leather, plastic, cloth,rubber, they come in all kinds of nice acceptable styles at very affordable prices, but can clearly not be called flip flops. If you work in any kind of professional environment where there's a chance you could be seen in public or by a client or other visitor, I'd be willing to bet flip-flops are a no-no.
There is a reason for that.
If you can afford to go to Disney, you can afford to put something on your feet nicer than flip-flops.
Flip flops also come off by accident much more often. When was the last time you've seen anybody's shoes or genuine sandals just come off compared to flip flops.
I guess I've just seen too many people in public recently in flip flops and hair curlers. If you're going to go out in public, please have a little decorum. Just a little. Please? If we all pitch in in this little matter, I promise all our experiences at WDW will be much nicer.
I also can't think of a real medical reason for flip flops as a priority that a slightly loose sandal wouldn't accomplish if you want to go the route of a medical excuse.
(Jumping off soapbox)
Can I get an agreement from anyone here?