This spell seems usefull, but mostly in a limited capacity. At 65, most dungeons are 60+ monsters, and most planes the same, or about any zone that nets EXP.
It's interesting, to say the least, that a 57 spell that charms level 59 monsters drops off a 67 mob in a GoD zone that is damn near the hardest place on earth to play (GoD in general that is, not that zone specific). Most people who can get this will not be hunting where they would use it. However, there is always a chance that they will be working over a 55-60 zone and need the AE.