I'm ok with it as it stands. It was a little too strict when they instituted the whole "signature dining" thing a few years back (and I got lambasted around here for saying so), but they've since relaxed it to a level that is appropriate for the environment.
There are things that are not allowed, and it is at least sometimes enforced. For example, we went to Jiko straight from the Animal Kingdom one day last summer. I was wearing a tank top but had brought a collared shirt with me. Since we got to Jiko right at our ADR time, I wanted to check in before I changed. After checking in, the manager quietly leaned over and discreetly and politely asked if I had brought a t-shirt or something. So they do at least sometimes try enforce it.
Even though t-shirts are allowed now, I personally still wear collared shirts of some kind to the signature-type places, but it doesn't bother me that somebody else wears a t-shirt. I really can't figure out why it should. How they behave and treat others around them is far more important.
I also wear shorts, simply because it's hotter than a.... well, it's really hot in the summer.
We just have to face it, WDW is a largely casual environment for a variety of reasons. The weather, the activities available, the number of children present, the fact that so many people are on vacation, etc.
It's pretty consistent with places like Hawaii, which has some fabulous restaurants, most of whose dress codes remain very casual.
This entire thread reflects how casual the U.S. has become. Have you looked around on a plane lately....Broadway show? Sometimes it is just a disgrace.
Not sure what to tell you. Have you looked at old films of
Disneyland? There's people there with coats and ties, high heels, etc, and that's in the dead of summer.
Should we go back to that? Can you imagine how those ladies' feet felt after a day touring the park? Or how the inside of that car smelled on the way home?
Really, I'm with you in that I think there are times to dress a little nicer, even if it's not "required". But at the same time, I'm happy enough to just do it myself and feel good about it without worrying about what somebody else is doing.
There's too many people in the world for me to worry about what each of them wears.
and the resorts when i go to Disney now. It wasn't like that durring my 1st 10 trips. 
