Simple math tells us:
Imp Bloodrage: 2 talent points for 6 rage per minute.
Anger Management: 1 talent point for 20 rage per minute.
Don't try and think of all the times the talent won't help you. Instead think of times where it will come in handy. There are a lot of fights in end game raiding with transitions and phases in between. Times where you aren't tanking anything, perhaps you're moving to another position. This talent helps you build rage so you're more prepared to pick up your target without it running passed you to the healer. I like it a lot