Epeen?
Whats wrong with a little friendly competition? When me and my friends play we love to compete at topping the dmg meter, its just damned good fun.
I don't do it for personal growth at all, just for fun! But as a bonus, it probably do contribute to me getting better also, because I work harder to win.
I can not see a good reason not to include it at least, if you don't want it, don't use it:)
And btw, where is target of target? When I'm tanking I really like to have that option!