Leave it to Microsoft to ruin a perfectly decent UI pattern
The iPhone first made the idea of UI “switches” popular, where you use your finger to swipe over an element to turn a feature on or off. A check box for touchscreen devices, basically.
Along comes Microsoft and they add this type of thing all over Office, including the element above to turn “Track Changes” on and off in Word. Let’s ignore for a moment the basic fallacy of taking a UI element that was designed for touch screens and blindly copying it to the desktop. You’d assume that at least they would keep the affordance of the “switch” metaphor intact, and let you click and drag the switch to turn it on or off.
Nope. Not the case. You can’t click and drag. You have to single-click (on any part of) the element, and then it animates and slides over. So it’s basically a checkbox that looks like a switch. And this is what we call a UI anti-pattern: A "recurring re-invented bad solution to solve a common problem."
Here’s my advice to Microsoft: you don’t need to be cool. Use a check box.