Good grief! Some of you must be a blast at parties!
Who cares? I don't care what you wear, you shouldn't care what I wear. Reminds me of a stay we had at the Grand Floridian when a group/family all dressed alike turned their noses down, and even commented out loud at what my teen son and his friend were wearing.... basketball shorts and t-shirts. I assume everyone should have been dressed in khaki shorts and polo shirts with boat shoes, like them. Some of the replies here, remind me of those folks.
Anyway, speaking of what Walt would want, how do you think he would feel about banning smoking in the parks? He was a smoker (look into the reason why CM use two fingers when directing guests) so I'm sure he wanted to allow smoking. Lets not pretend his visions would still apply today. Times change as do people. Disney is a business and is run like one. They will target as many audiences as they can, in an effort to make a profit. I would think there are bigger, more important things to be worried about, other than t shirts.