Some of us don't have very much idle time at all, I might afk to run to the store, but I bet my count's pretty accurate otherwise. Perhaps in the future they could make it so if a character doesn't move for ~10 minutes the clock stops counting, and provides a distinction between play time and idle time?

Example:
You type /playtime and it shows
Play time: 42 days, 7 hours, 6 minutes.
Idle time: 1 day, 4 hours, 17 minutes.

Really though, I'd be fine with just the amount of time we've been logged in.