You've received so many replies already, but mine is different. The older I get, the less I want to deal with the video game-like elements of hand-eye coordination, intense visual attention, and timing. I'm tired of things going wrong because I clicked a few pixels off or clicked on the wrong thing because I was surprised by a UI element appearing in a slightly different place or with an unexpected delay or with slightly unexpected contents because of a software update or just something I didn't predict.

With keyboard commands, I don't have to verify the accuracy of my mouse movements, and I don't have to react to the timing, location, content, and focus changes of UI widgets. I just press the keys in the right order. It requires so much less vigilance, it's a big relief.