"So is the general feeling that you shouldn't own a BMW out of warranty?"
Like everything, "It all depends". If you want a 2002, the only way to drive one is to buy one that's out of warranty.
The BMW mechanical stuff doesn't bother me (well, not too much). But the electronics took a step forward (or backward) in complexity and serviceability from the E46 to the E9x.
My E91 has had multiple electronic poltergeists and required several software updates and reprogramming. That's difficult to do without visiting the dealer.
(Since the F31 will not be available in the US with a manual transmission, I won't buy one -- and I have mixed feelings about that. The E91 is a lot of fun to drive. The maintenance issues have been an annoyance, however. I may go Japanese for my next DD, just so long as I can get my manual transmission fix.)
2008 E91 station wagon 19K miles "Classic" BMW inline six, six-speed manual transmission, Alpine, Terra, Xenons, ZSP, ZCW, ZPP, PDC, CA, alarm, M shifter and M brake handle, Euro rear fog light switch, Euro aspheric mirrors, rear power outlets, Euro split armrest, Garmin nüvi custom cupholder mount, Lidatek, V-1 built-in remote display, tire pump, jack, floor mats, sand, dog hair, several pairs of smelly old running shoes.