Raising PPs preflop

[echinos]

I've seen a lot of advice saying that most pocket pairs (in both SSNL and SSLH) should be raised preflop. I generally raise with TT+, but after that, I limp for set value. Below TT, very often I end up folding on the flop or turn after an overcard or two shows up, so I don't see the point of raising, unless I'm doing it as an isolation play or something.

So, should I be open-raising with 88 from MP every time?