The idea (at least from my POV) isn't that the AA is broken, but that the ability to root a mob isn't very useful in terms of a wizard's primary role: DPSing mobs, and that it is pretty redundant when you look at two other wizard rooting spells.
The ability costs 17AA points if you buy all the ranks of timer-reduction, (which I assume you would do were you to actively use it; it is COMPLETELY useless while the refresh timer is a-tickin) a price which I (and a few others-though admittedly NOT ALL wizards) am loath to pay, especially in light of the existence of Taratzu's Infernal Trap: a dropped wizard-only root spell with a good resist adjustment, and the regular spell Shackles of Earth, which has a lengthy duration, no recast timer and is not resisted consistently enough to make it unsuitable for most situations.
I would prefer to see the AA replaced with something that EITHER:
Helps with a wizard's primary role in raids and groups, by:
-helping to regain mana a la an AA harvest (perhaps this could be balanced by returning a flat percentage of the wizard's mana rather than a raw number: 5%, 10% maybe?)
-increasing nuke damage or critical chance for a short time a la the beastlord frenzy of spirit AA
-replacing the root with a mana free, fast casting, unresistable AE nuke for less damage than life fire.
OR:
Gives wizards a useful ability that we don't already have in spades.
-I don't have any specific awesome ideas in this vein but I would love to hear some that don't unbalance the class or change their overall role.
-it might be cool if we got some kind of group or raid AA that helps others. I don't want a copy of the Magician Elemental Barrier AA but something like that; aside from rbow there really isn't much for a wizard to do to help his compatriots in battle.
Final Note: I hope people actually read this far before responding. I'm not trying to bitch or complain about the AA in general, but I do think that changing the ability to something that is less redundant, and more useful would make it a better AA. The way it is now I would prefer to have more mana (from other AAs) or do more damage (from tomes) than spend points on this AA. I think one of the best parts of SoD is that players have the opportunity to say what they do and don't like, and how they would change it. Nobody's forced to think I'm right but please at least read the entirety of this post and consider it.