I'd like to put in my two cents on this subject.
Bicycle clubs, perhaps from their inception, have come in three varieties:
1) The social club (these haven't been particularly popular in the USA since the 1890's as far as I've been able to tell.) You can read reports of these clubs riding down the road in ridgid formations two abreast and in military order. Most of their club activities seem to have been based on the non-riding activities. Banquets and the like.
2) The racing club - unfortunately MOST clubs like to think of themselves as racing clubs and treat their rides as "training rides" instead of group rides. Even more surprising so few of these clubs even know the purpose of a training ride. These rides turn into a chase with the strong men attempting to drop everyone else in a blatant display of ego second only to those guys who drive Cadillac Escalades to work every morning. While this might appeal to young riders it is a very strong turn-off to most bicyclists and is the reason so many clubs fail to grow. And yet of the 20 or so clubs in the bay area every one I've been to has been this sort of ride save my own club.
3) The group clubs. These are surprisingly rare and I'm happy to say I belong to one. One of my foundest memories was a ride about 40 miles long. The group was cycling along with me near or at the front. We were going around a bend on a nice road in the country on a sunny, warm day. I glanced back and each rider in the line was wearing a different jersey so that the colors were shocking and looked like a painting of a French Master. The slower riders had to ride a little faster than then wanted to and the faster riders a little slower but that day everyone simply enjoyed the group ride to its fullest.
There are rides in which you want to test yourself. There are rides in which training should take priority. But club rides should be based on the idea that it is a CLUB first and that you don't want people getting lost or left behind to find out that their spare tube has worn a hole in itself in your seat pack, that the glue in your patch kit has hardened or that your pump has ceased working with the dissolution of the seal.
Once I even found a woman upside down on the sharp slope at the side of the road unable to release those old Cinelli "clipless" pedals and get out of the bike. Her husband had dropped her and she had been like that for 5 minutes when I found her! Tears aren't the half of it.
Maybe it's because I'm older that I so enjoy group rides but even when I was racing I would ride in the group except on the climbs which I'd use to do the necessary training on group rides.