Yes, when not MT, not going berserk is very frustrating. That is what I use this abiliity for, very few other things, unless I am soloing somethign tough, so I can go berserk right away. IF I am MT, it is not used at all, focus rage does the trick for me.
I hear we get an ability that makes you go berserk when the group is attacked (% chance), that would be a nice addition.