On my Dell XPS replacing the battery also only involves unscrewing a few screws and unplugging one connector, then putting that back together with the new battery. It couldn't be simpler, and that's in the space constraints of an ultrabook.
On phones there's a better case for fixed batteries, but at least I don't mind another millimeter thickness if that means I can replace the battery.
I miss the good ol days when my T410 just simply unclipped. Completely modular, no screwdriver required, almost like battery replacement was a feature!
For a while, up until the T480, you had both an external and the internal battery. So if you had a few batteries it was pretty trivial to swap them while on the go--and sometimes you really do need 18 hours of battery life on a laptop, even if you aren't pleased about it.
On phones there's a better case for fixed batteries, but at least I don't mind another millimeter thickness if that means I can replace the battery.