It's said about brain that, "use it or lose it" — now, question being, do you think if person plays brainless gambling games such as slots, dice for major part of his/her daily routine, will it make him/her dull?
Edit: "brainless" as in playing gambling games that does not require using brain, I thought it was clear especially given examples.
My question to you is, is there anytime we don't use our brains?
If you are going to talk about gambling games that does not require skills, then you should consider those feelings of excitement, anticipation and sadness that comes with playing those games. That's still the brain working even though there were very minimal mental analysis and calculations. You can't really say the brain isn't put to use when playing these kinds of games, there are still some moments when you begin to think what next to do to make sure you win. You might not be putting facts and figures together but the brain still goes through alot.