When I play a Troller, I use the hell out of my Immobs...they key difference though, is that I wait until the baddies stack up on the Tank. Then I lock them down so that the Blaster can be free to annihilate with their AoE, Scrappers can focus on mobs without running all over creation and Tanks get their bonus defenses/regeneration/recovery for having large groups of NPCs within their range.
No power is bad if used in synergy with the team. But all it takes is one player to disrupt that synergy. Your Trollers could have held off just a few short seconds when attacking mobs to let the Tank gain the Alpha and Aggro stack and they could have unleashed their unholy hell upon then, heh.
It really depends on the team though, sometimes, you get a team without a Tank and maybe the blasters are fine with the instant immob...for me, I find that it is always best to start playing the style I typically play, get a feel of how the team plays and then adjust from there.