That being said, it's not a skill I've ever trained, because like you I've always seen a better place to invest my Training Points. But like all skills on every Gearloc, I'm sure there are strategies of playing Tantrum that employ this skill well, even if I've never gone that way!
Anger management is useful if you want to actually use Rage #2/#3.
Otherwise by the time your rage naturally upticks 8/12 times, the battle has already been decided. Anger management can help get an early 5pt baddy execute, which is useful, albeit a bit situational.