I made this suggestion back on Eorzeapedia like a year ago and everyone shot it down :/

Basically the idea would be if a certain group of players continued to monopolize a specific NM instead of the GM's just kicking them out of the area to let others have a chance they could take control of the monster and it would take on a "Pre-Rage" status where they are not fully raged but are more powerful and the GM controls how it acts. Thrashing healers instead of wailing on tanks, etc.