There shouldn't be a toggle for such things. It would give an advantage to the players who don't care about the atmosphere of the game, so everybody would just have them displayed. I like adventuring and seeing bigass monsters and wondering if they aggro or not, so I hesitate to just walk passed any of them, or to ask around.... "hey, i see a bigass monster, does it aggro?"

That adds an element of feeling and realism to the game. Do we really need SE to hold our hands when walking from Point A to point B?