Tilt can and often does play a huge factor when playing heads up even at high limits. Whether these people are "dumdums" or rocket scientists is irrelevant.

Against most opponents, I agree that not 3-betting pre-flop can be made up for post-flop. But against tilting or ultra-aggressive opponents, you could be losing out on bets.

"Third, in this specific case I would greatly prefer to have called preflop. It's going to be much harder to figure out that KK is no good after I just call preflop. Even if he knows I never 3-bet my possible hand range is still larger and the chance of AA correspondingly less."

To say it's going to be much harder to figure out that KK is no good after you just call pre-flop is absurd. An average high limit heads up player 3-bets 20% of his hands pre-flop (I have 270,000 datamined hands of 300-600 to prove it). AA accounts for .45% of that 20% hand range. That means your opponent can be roughly 2.25% surer than normal that you have AA. After an ace flops, you only have three ways to make aces instead of six so he can't even be 2.25% surer.