I think thinness is overrated too, as a device thinner than ~10mm starts getting rather difficult to pick up from a flat surface and hold comfortably (I have big hands.)
edit: a phone you could "sleep" the RAM to capacitors for 30 seconds and swap batteries in without restarting would be awesome. Kind of like the old Palm devices when you swapped AA's.
(n.b. I don't mind if they're user-removable for replacement once they've totally died, but this also seems to have become rather rare for what I assume are manufacturing reasons)
For myself, I'd rather have a long-lasting integrated battery than a removable battery. For example, my current laptop (recent macbook pro) with its integrated battery lets me work the entire flight from SFO/LAX to AMS/CDG (10 hours). Whereas my previous laptop would make me change the battery just to go from BOS to SFO (6 hours) and even then I was running out of charge on the second battery.
Does anyone know why the integrated batteries aren't more form-fitting? If you could have the battery fill all of the empty spaces you could probably get even better charge. Are 'pourable' batteries possible?
Yeah, LiPo batteries are quite flexible, but the problem is that you have to balance multiple different-sized subcells when trying to fit battery in every cubic inch of space in your laptop.