I think it would be fun to know the real veterans from the professed veterans, but I don't think exact account creation dates are the best or most fun way to do it. Actual in-game veteran rewards and titles would be much more fun, in my opinion, and could be listed in the Armory.
What information would you like to see added to the Armory? Do you think that account creation dates would be useful? And is it really necessary to call my poor neglected druid "untalented" for all the world to see -- in capital letters no less? Yes, I haven't logged on to her in years and her talent points are now reset and unspent but that hardly means that the poor thing is not gifted. Wouldn't "unknown" or "undecided" convey the same information without being so pejorative?