Of course, 1979 MGM Las Vegas is actually present day Bally's.
If you recall, there was a fire there in 1980, which killed 80 people. It spurred a massive worldwide change in hotel safety. I stayed in the MGM in the early 80s, and it was the safest place in town at that point. They even had a TV channel dedicated to fire safety.
These tokens were an integral part of old Vegas. You couldn't walk through a casino without hearing machines ringing and the clanging of tokens falling. While slots are now far more advanced and resemble video games in some ways, I still think they don't have the allure of the old slots with the money clanging down.
These were, of course, replaced by the current "ticket" system. While far more convenient and easy to manage, there was something satisfying about scooping up tons of those tokens, putting them in a bucket, and taking them to the cashier.
Sorry for the sideways pic.