I don't commute, but if I did I'd log them. Seeing other people's daily 2-mile commutes in my dashboard feed isn't particularly interesting, but miles are miles and they all count. I have been known to log stupidly short utility rides, anyway, on the rare occasions that I (a) take a bike, and (b) remember the Garmin.
Agree with Kim that it would be good to have the ability to add luggage weight.