I found it pretty easy; I went from an asus transformer (14 hours real-world, and I did use it) to a samsung ultrabook-like (<4 hours). Just get in the habit of plugging it in; how much of the day do you really spend away from a power socket? It might not be for everyone, but it's been fine for me.
>The moment I need to bring the power cord and adaptor with me, portability goes to "desktop replacement" levels.
Surely you don't just carry a tablet in your hand when walking to the office? Once something's too big for pockets I resort to a messenger bag over my shoulder, in which it's just as easy to include the power. Given that tablets don't seem to come with cases, how else would one transport it?
Working in the office is not working on the go. Working on the go is finish up stuff and send it before boarding a plane, or work on that same plane, or during your train commute.
If you're going from home to the office and back, I don't see the point in carrying anything other than your smartphone. Talking about the general case, obviously, there are justifications for bringing a medium-sized laptop.
I get things done in all those cases on the setup I mentioned. Obviously if you're taking 8-hour flights then you need that much battery, but is that a common case?
It's a very common case that you have a hard time finding a socket in some places. It happens a lot to me that many others are working on their laptops and all sockets are taken, or even that there are no sockets at all in some trains.