I think they should go even further, and have mobs that aggro based on a variety of other things. i.e., touch, for one (just makes no sense that you can touch an aggressive mob, as long as you're behind it)
What about territorial mobs-- that attack if you intrude on their territory? Maybe mobs that attack depending on if you have food, mobs with different aggro personalities, etc. There are lots of cool ways they could elaborate on the aggro system.
Those would all be excellent. Tremor-detection for mobs like worms and whatnot, too. Also, I'd like to see mobs that threaten before they attack, especially if used in conjunction with a territorial mob. Get near it's territory, it threatens you (even if it's just an emote-like animation). Enter it's territory, and it'll actually attack, but only until you leave.
FFXI had a good aggro system, but it had a terrible way of controlling it. I don't need sneak to wear off every 10 minutes (or whatever it was), stop resneak a party, and then go on again. Poor mechanics basically made a good system very tedious and that needs to be addressed. It was even worse when you needed to invis also..
oh.. I can't remember the last night deodorize was useful... maybe it's me.
Yeah, the spell mechanics are horrible. A fixed duration would solve most of the problems.
As far as Deodorize goes, it's one of those spells that's saved my **** a small handful of times, and might have saved it a small handful more if I'd actually remembered it existed. If there were scent-aggro mobs, though, it'd be a lot more important.