I visit casinos in Las Vegas and Atlantic City regularly. I see based on carts (with remnants of meals from room service) left outside the rooms--lots of gamblers (and others(?)) are using RS; probably it is a complimentary item for high level gamblers, I can't see (except in an absolute emergency) others ordering RS--the prices are 5x-10x what they charge in the coffee shop, and if you were to eat at the buffet (with unlimited selection), a single RS item might cost as much. Add the mandatory service charge + the tip to the person who delivers the food...a "rip-off" IMHO.
[Side note: some casinos are experimenting with in room gambling on your TV--so a person could visit a casino and do all their gambling and dining, while never leaving their room.]