With Flash you can very easy use the keyboard for all not map related playing.
Which means, that you use the mouse only for deploy/attack, while you can control the game session with the other hand from the keyboard.
In UJS now comes a nasty warning, when you try to commit a session without attack, which don't react on the keyboard. So you must take the mouse to click on the OK button, to continue.

Why this dialog can't be controlled with keyboard as well? I would like to control this dialog either with keyboard commands or to disable it totally in my settings.

Yes.
Also I like to do deployments easily with keyboard in flash; in ujs sometimes we have to keep the cursor in deployment box to select it and then change it or make it 0.