mental games are amazing, as far as I know the greeks were the first to kind of lay off and think about things, got us lots of good results, things that are pretty fundamental to life, well the first we kind of more democratic about it, even with slavery to back it, it wasn't just the king and the priests that could read,
So about the mental games, that's pretty important for the vitality of the mind, I'd probably agree more with you, but I do think those getaways into the past/present/future come from lack of engagement or inability to handle the situation, that or plain letting yourself be bored.
Which again, usually does good, I don't know how you could have an abstract mind and form all the theories without being distracted by the fantasy and letting yourself go with it, that's how innovation comes I'd say, taking a new look at a old problem and seeing past it.