A minus sign and a hyphen are the same length: a short, single line (-). From a typing standpoint, they're interchangeable. You'll use the same key to make a hyphen or a minus sign, whether you're connecting two words or writing a mathematical equation. The em dash is longer, and...
I propose this shortcut for being added as a default, because I am used to it in Sublime. It's incredibly intuitive being able to comment out a line at the press of the key that's actually used for commenting. I can understand that I could just get used to using CTRL+K, but I h...