I finally learned that besides the middle mouse-button, you can also use ctrl+click to power rooms, but this seems somewhat unhandy in some cases.



Let's take the example of Tablets, since that seemed to have won the vote some time ago.

Tablets come without keyboard(at least, most don't) nor a mouse. Currently it would be impossible to play for them. (And I know, it's not made for tablet currently, but just saying)



By adding an icon that can be clicked on (An example of a game using this is Rimworld) you're creating another option to play the game without constantly needing to grab your mouse.



Just throwing my opinion out there.