If Vegas wants to keep ahead of all of the Indian casinos, riverboat casinos, etc. then having a classy casino with a dress code is not such a bad idea.
When I go to Vegas I like to dress in a sport coat. I find I get treated better, and I even get hit on by better looking hookers! ;-)
They have it, it's called 'Bellagio'. Dress code is (was?) in effect at all times. They don't throw people out at 6:00 pm.
was = maybe rules have changed, it has been awhile since I was at Belaggio.