Not raising Big pairs PF

[Frond]

OP here. I think that maybe because I am starting to play more live LHE that I have been seeing a lot of limping in with big pairs. They are also the ones who are always calling and rarely raising at all. I guess because that I always raise em PF and reraise em that I am still a bit astounded when people flip over KK on the showdown and they won the pot but failed to raise the hand PF in or out of position at all. I am so programmed to play my agg PF style with big pairs that I am not yet used to it but I am starting to see a myriad of lame plays and trying to file them for present & future use.