The dominant hand should be the one that keeps you on the road, but it means you can't drape your arm through an open window to show off your watch.
I'm glad I learnt to drive in a manual, like I'm glad I learnt to drive a tractor down a wet grassy slope with a two-ton roller on the back, but it would be tiresome to be practicing these skills every day. Manual changing is redundant for ninety percent of the time, and as you get older you care less and less about the other ten percent.
Anyway, it's a skill you never lose. It's kind of fun to drive my wife's manual, but after a mile or two I've had enough of it.