I don't mind that my phone battery is sealed up. I do mind that I have to bring it to a specialist that might screw it up and make me pay for the privilege.
Actually, this bothers me way more with laptops than with phones. With laptops, there's no water resistance or any other reason besides thinness to seal the battery up. Particularly with business machines, the computing power will be more-than-sufficient for many years to come, yet many will end up in the trash because the battery's no longer doing its job. It's ridiculously wasteful.
All of them. You could argue that the time and expertise needed to replace a laptop battery is negligible, but I say it's an unnecessary increase of time and risk required to do so.
What do you feel are the benefits of embedding a laptop battery in the case?