I've had my linkshell do a few regimens , even I was surprised to get 1.5k damage on a mob compared to everyone else's 100-200 damage ... however except for the number, its not very noticeable . I've even made a video on that too ...
after that, we were using them without argument as to whether they were a waste of time and effort or not.
Getting people to want to do them would really, really help. It is hard work, and I'd want to see that paid off with a nice animation and damage numbers separate to the attack itself (say if thunder did 500 normally, show thunder doing 500 and the effect doing 1000 damage. Or say a defence down regimen ; attacks do the damage they would have done + bonus damage in a different colour).
(Anyone want to see the video of that thunder ? =P)