1) If you'll only ever go AI PF w/ AA, assuming you 3-bet wider, guess how wide my PF push range is going to be against you?
2) I would only ever consider limping KK in EP if I was 99% sure some aggro is guaranteed to raise in position... and that's only so I can 3-bet his ass. Limping for limp sake is a great way to get stacked, usually followed by some comment like "DAM FISH! U SUK OUT WITH 59 U SUK" on a Q59xx board (not implying you'd do that...)
3) You only have top pair with 2 outs to improve. That's 2nd nuts preflop, and then goes down in value fast through subsequent streets depending on board texture. You want money in fast, and pref vills out fast before they get a chance to draw out on you. Raise, re-raise and make them pay to play or force you to reevalute.
4) Ideal SPR with a top overpair runs from 4 for tight players to 7 for looser. With AA-KK my opening plan is getting all the money in the middle heads-up. So I want to raise to build a pot that'll let me do that -- pref with 2/3psb type bets that are much more likely to get called by AQ or QJ on Q492x boards than 2x PSBs 'cause I didn't build my pot from the gate.