I'm one of those people who "still" think that Agro indicator and telling people the mobs level by default is LAME.
I disagree, for only one reason: All removing this would do would mean you learn what aggros after the first time it kills you. After that, there's not really any difference. Stuff's still going to aggro you whether you know it does or not. The only thing this eliminates is the first-time "I didn't know that aggro'd", unless you're too clueless to remember things like that. thus, to me, it's a harmless feature.