I think you have several good pieces of advice, not the least of which is drop it for now,and convince them that all kids have to sign in (I love that one!), and get into the teeth of it at the sail away party perhaps.
However, some will like it and some wont. You know your kids best. Do they join in? Do they socialize easily? Are they shy? My son never did take to the club, and after his second
DCL cruise at age 6 proclaimed the activities boring--and 6 year olds are not going to get bumped up to the Lab, I don't think. As an 8 year old he wasn't interested in much except the PS2 at night in the lab on the Wonder, and on the Magic as a 9 yr old they didnt even use the PS2 much, so he bagged the Lab, made friends at the ping pong tables and basketball court, and hung around with these new friends the rest of the cruise.
We tried hooking him up in advance through the board, and thought we had a good match, from our same state, but then the other boy blew him off on board. I'm not too worried about it being something my son lacks, he is very popular in his school, an all star athlete in two sports youth leagues and a straight A student in a gifted program--doesn't seek to be the center of attention, but he was a full time day care child from a young age so the group setting is natural to him--it was just a case of the programming being too sedentary and story telling for his more active tastes.
So we had 3 DCL cruises with my beloved son being frankly a pain in the tush hanging on mom & dad, and finally broke through on #4 and got time to actually relax.
Oh, and on cruise #4, before he met his buddies and proclaimed on our Sunday day at sea that he was bored,I told him all the options available to him, none of which involved nagging me,and that if he couldn't get with the program then when we docked at st. martin I would take him in a cab straight to the airport, get on the next plane with him to the states at a cost of perhaps thousands of dollars of walk-up fare, go straight home, and there would never be another vacation for the rest of his childhood. And I meant it. I think he and Joey got hooked up at the ping pong table an hour later.