Short handed, when effective stack vs blinds is too low to set mine/your number of BB is too high to shove, pocket pairs only have more value if you're willing to go to show down with it.
Against certain ranges, you're dominated against higher pairs and only a slight edge over over cards. On most flops, we're either forced to c-bet into a scary board or forced to check/fold our hands and try to get to showdown cheap. We might flop the set 1:9 times, but if the odds
/ implied odds aren't there, then it isn't profitable to play the PP for set value.
Don't get me wrong. A pair is a powerhouse short hand and vs less people, it'll win more often. But this is usually only if a) we're picking up the pot pre-flop or b) we get to showdown with the hand...and also, it'll depend on factors like position, stacks, opponents, weather, the stock market, etc...
...Random thought. I could be completely off.