Hmm!
That's a good idea.
Testing it out a bit, I find Mind Vision does in fact work without any line of sight. I can Mind Vision an NPC from outside it's building, so in theory you should be able to Mind Vision a player with a flag so long as they're in range.
That would actually be immensely useful. Defensively, if you want to know if they're coming down the slope, tunnel, or cliff/graveyard from your base so you can effectively tell the team how to intercept them. Ultimately, I think the power is in Offense. Flag bearers like to hide, and there's a number of little nooks and crannies they can stuff themselves into on either side of the playing field. Even if it took you a few seconds to target and cast, it's less of an issue offensively than defensively because instead of trying to locate an opponent fleeing out of your range your approaching an opponent whose intent is to wait.
As for the macro, I'm in the same boat as you.
I just can't think of anything beyond the simple "target the person manually and cast".
For the sake of expediency when typing, you can shorten /target to /tar.
Also, the first two letters of the Flag Bearer's name instead of the whole thing.
for example:
/target zemzelett
can be reasonably shortened to
/tar ze
Maybe a resident macro guru can do better?
Edited, Feb 24th 2009 2:32pm by Zemzelette