I'm deciding laptop ergonomics are really important (but $1000 important? cringe)
I swallowed the extra cost when I did the math. I use my laptop about 3000 hours a year. Day in, day out, I'm on it in some way. They usually last me 2 years or so before I get the itch to upgrade or they fail. I did the math and found that the ~$1000 laptops I bought cost me $0.003 per minute over the course of those two years. A $1300 MBP cost me $0.004 per minute. I decided that I would rather pay $0.001 more per minute to enjoy the hardware I used. I'd rather be in a rage over the fact that my code isn't doing what I want than if my battery isn't taking a charge again.
An added side benefit has been how much tougher the MBP is. I've had it for two years now and it shows no signs of needing replacement. I probably won't upgrade until I see how Apple's Retina display transitions to their laptop line. The upgrade then will probably be out of lust than necessity.
We're talking about the primary tool of our trade. I make my living using this device. If I was repairing cars again I'd be buying Snap-On. Yeah, it's expensive. But goddamnit if I break a wrench they replace it for free. The guy drives to my house and gives me demos. I don't need my tools giving me grief, I need to get work done with them.
Just my thoughts on the 'Apple tax'.
MBPs are not that tough though, I've a colleague who really shouldn't be left alone with machines, his MBA (which he brings everywhere and takes little care of) did suffer quite a bit, it's horribly dirty and has quite a few dents. A Dell half the price would probably be dead already, though. But he'd probably benefit from a Toughbook C1, that's a step up in ruggedness, MB's aluminum is nice but not that solid.
All that to say the trackpad, keyboard, keyboard controls for display brightness, and (my experience, obviously not common) battery longevity do seem to be worth the money. There's a ton of weird little pieces that apple really gets right that don't show up on the spec sheets.