You've never tried to explain something to some one who is computer illiterate, have you?
Sure, it's easy for some one who is used to computers to *remember*. There is the key word.
I'm sure I could show my mom that she does this gesture to go back home, but I also know she'll keep asking me cause she'll forget. And I know once I'm gone (I don't live in the same state), she'll forget and get frustrated.
The button is great for her cause I show her the button. And if she forgets, at least when she looks at the device, she'll see the button, it reminds her it is there and all she has to remember is that she presses it and it goes home. It's much simpler to remember to press a button than remembering a gesture that doesn't even have anything to remind her of what she is supposed to do.