Even though I know roughly what time it is (probably to the nearest 30 mins) all the time, I still like to have the ability to know the exact time just by looking at my wrist! And no, there aren't clocks all around me...when I'm on a computer, that's fine, but when I'm out and about, its often not that simple

Its just a comfort thing for me. I would feel naked without having my watch on every minute of my waking day.
It's a bit like wearing glasses...it's just always there so you don't notice it, but it serves a vital purpose. And the mobile clock is useless...it doesn't have seconds. Having said all that, I would never have a watch as a fashion accessory...purely functional.