Fundamentally the mouse is just a form of modal editing. Emacs supports this in spades of course, and god-mode is my modal input minor mode of choice, but clicking to jump to a position on screen can often be a lot faster than I search or avy-jump commands, say nothing about how much gentler on the wrist it is. Then you can customize the menus and toolbar icons so you can be 1-2 clicks away from something that would otherwise require a chorded keypress or worse, an M-x command.
Then you have the biggest benefit of using the mouse: scrolling around reading code or text while having a drink or snack in the other hand. These days I use a trackball in my left hand. Regardless, the keyboard vs mouse thing always struck me as one of the many dumb flamewars that tech people engage in.