It is my feet and my gun and it is up to me if I want to risk shooting the former with the latter.
I'm always fascinated at the threshold where people will decide something just won't happen ("useless") because it's not comfortable enough.
I'm more in the camp of pushing the limits as far as technically possible if it means I'm neither walking around with a 13" screen at all time nor need to be home to be able to look at two things at the same time.
So I'll be fine with readjusting a bit the window to input text if it means I can do the thing now instead of 6 hours later. At least I don't want Google to kill the feature just because it requires working around some quirks.
I rarely use split screen mode on my Android phone but I am rather annoyed when I'm on iOS and I can't keep two apps open at the same time.
Some vendors do a much better job than others, though. Google in particular doesn't seem to offer more than the bare basics.