I thought about this some more and came up with the reason that I like to limp these hands:

1) I don't have a problem laying them down to strong shows of force by tight players, so I don't lose very much on them.
2) When I hit hard, they pay well.
3) When they make 4 to a straight, the tables I play are usually so passive that I often catch up for FREE. Even when someone else hits, they try to slowplay and give free cards. These hands can draw to the nuts, and then the guy slowplaying you gets pwned.

Thanks for the feedback on this. I feel better now =)