Have you walked past one recently? Casinos used to have at least some veneer of sophistication - polished wood, baize, well-dressed croupiers - even if it was ultimately pretty thin. Now the whole room looks like a giant kiddie noisemaker toy.
Aside from general infantilization, another theory: The old status-signalling has moved on to something else, and past generations' signals of upper-class (or at least classier) gambling are now obsolete, so nobody bothers projecting them.
