What limits are these hands from? I know sample size would reduce but I'd like to see the breakdown by limit. I think as you get higher, raising becomes the better option, for 2 reasons:
1. less people, especially in an unraised pot, will stack off with TPTK or other hands where bad players will pay off your set incorrectly.
2. Smarter players, they will begin to pick up on the fact that an EP limp means low pp set mining.
You mentioned #2, but I think #1 is the biggest reason, just because you are sometimes no longer getting implied odds
to set mine, because you just won't get paid off enough.