Like you say most windows laptops have such garbage battery life already that it's not practical to use them unplugged.
So, a simple computer? You can even choose your keyboard, mouse and screens.
It does kind of seem like, outside a few select models, the PC market just gets the laptop part of laptops so so wrong. Bad touchpads, bad screens, no battery life, unpleasant industrial design usually, crammed with crapware and other bullshit. I hand it to the few companies that do try harder to remedy these.
For all that extra bulk it ought to be extremely robust and repairable, have the best specs possible, and be equipped with the kind of killer cooling system that a thin chassis can't deliver. Then the tradeoffs might make sense.