your educated guesses about the reasoning behind tight pre-flop play are correct. there are indeed mathematical quantifications of the expected value of every 2-card hand. these have been derived through both computer simulations and from actual hand histories of real poker players.

you should only be seeing the flop about 20-27% of the time, including the BB. there are obvious hands you should be playing like AA/KK/QQ/AK. there is obvious junk that can never be played, like 52 offsuit. then there are marginal hands that seem to win sometimes, but actually lose a hell of a lot more often, like 65 offsuit and A5 offsuit. then there are hands that seem good but are actually long-term losers or breakeven hands, like KT offsuit. these are just a waste of your time, adding unnecessary variance to your bankroll.

the idea behind raising a non-pair hand like AQ suited before the flop is simple. you expect to miss the board most times, but on those times you hit, the pot will be much much bigger because every raise you make adds many bets to the pot (from the other players). so the few times you drag a giant pot more than make up for the times you miss and lose just one extra bet.

it's like doubling down on 11 in blackjack. you cannot possibly expect to hit a ten every time. but when you do, the 3:2 payoff makes up for those other times you missed. so you have to do it every time, consistently, and not on a whim or a "feeling" that "this time" you're going to hit. otherwise what will happen is you will raise one time and miss, then limp in another time and hit, but the pot you drag will be so small it won't recover your previous losses.

search the web or pick up a poker book and you will easily find a chart of proper hold em starting hands. those who stray from the recommended starting hands may get lucky from time to time but will end up losers in the long run (unless they are true experts in post-flop play).

ChezJ