It's expectation. Think of all the screens in your life that you interact with and when you can't touch them it feels broken (at least to me). So I don't use my laptop as a tablet but when some dialog pops up I want to touch the cancel button. Or I'm helping someone with a task and reaching to move a window directly is natural.
> when some dialog pops up I want to touch the cancel button
I have never had this. I don't think this is the expectation among people using laptops either? Pressing escape is much faster, doesn't obscure the screen, and doesn't require me to aim.
So it is just table stakes at this point.