I think it is fine to limp with them as long as you limp other hands as well.
You don't want to limp only with AA, KK and raise with everything else or limp with your junk hands and AA but raise with everything else.
If you play that way, people can put you on a fairly accurate range of hands and it makes it much easier on your opponents.
I feel the same way about raising less with you strong hands and more with your weaker ones (preflop). You can vary your raise sizes if you want but it shouldn't be based only on the strength of your hand.

eejit also makes a good point. People see AA and feel that they are supposed to win with them so they'll go broke with a hand that should've been folded on the flop.
I had aces cracked twice yesterday. However, one hand was all-in pre and in the other, there was only a pot sized bet remaining post flop.
But, if the stacks are deeper, you have to be skilled enough to recognize when you are beaten and not go broke. I think most of the online players are not disciplined enough to lay it down so they would be better off trying to get more money in preflop.