I haven't had too many issues with groups just sucking. There was a group that didn't have enough dps to down the bonus boss in mandalorian raiders.
This used to happen a lot on most bonus bosses early in April. If you have both dps below full 150 gear, you may face some problems delivering on the dps part. Considering how is easy it is to get basic coms and elite comms, I rarely ever see enrage in FPs anymore.
I also was tanking a group on final boss of Cademimu and both dps died. The healer and I ended up doing the whole fight. It was so much fun too! I guess that boss doesnt enrage. Im not sure how good jugg tank dps is and I had to keep doing shackles on healer. But that was the most fun Ive had in this game.
I had similar experience in the good old days of when the shackles were unbreakable. Both dps died by the shackles early in the boss fight. I told the tank not to worry about me (I am heal sorc with root remove on force speed), and the boss does not enrage and does not deal much damage so I was dpsing in between barrier and Hot cool downs. Downed the boss with no problem.
I do kinda agree about the loot. Really no reason for half of the bosses in each FP to drop useless loot. 2 comms per boss is soo measly as well. If you get a loot ninja in this game, it can be soo heartbreaking.
FPs give 19 elite comps per FP per day with bonus boss. Mostly everyone do them now because they are trying to get the ultimate comms from the weekly though.