I agree, and this seems to becoming quite a problem with signature dining at WDW. My party and I got dressed up in 2011 to go to dinner at the California Grill, heck, I even wore my best belt, and still felt like we had walked into an Outback Steakhouse perched on top of the contemporary. Fortunately the food and service made up for it.
I think Disney should seriously consider 21+ sections of signature restaurants or time slots where only adults or families with children 13 and up can dine.
But you hit on the heart of it, Disney doesn't think that having rubes at fine dining locales is bad. They want the family of six on the DDP to come into the Cal Grill and 'we'll all have the steak with none of that funny sauce or veggies, we want fries' ... And that's why they've dumbed down the dress code yet again . Now, tees are fine provided they don't have offensive words or imagery. REALLY??!! You are a fine dining locale and that's your code.
As much as I love CG, I wonder how often I'll dine there in the future. Much better to go to a place like Il Mulino where the rubes feel they don't belong and Disney hasn't twisted arms to get them on the DDP. People are dressed as they should be (only one guy with shorts and he was at the bar), kids are minimal and well-behaved and there are more than 6-8 choices on the menu.