It seems as if clubs are working for people who are either part of a close knit circle of friends and family or had been trading with each other long before this feature was added. For everyone else, clubs are pretty pointless.
Naturally, if you're part of a closed club with friends and relatives, it's easier to trade. Because everyone in the club is likely going to be in the same time zone, it's easier to coordinate trades. You just tell your friend, "Oh, I'll be on in an hour, let's trade then," and it's all good. And chances are, because everyone knows each other, no one's going to snatch a trade out from anyone's noses.
When you're in an open club, it's a different story. It's a disaster. You want to do a one to one trade with a member, but there are 23 other members from God knows where lurking to see if they can snap the items up. Everyone's in different time zones so asking for stuff is pretty pointless. You will ask for dozers and it might be another four hours before someone turns up with them, and by then you're either at work or asleep or off doing some errand.
At first I was also confused by clubs but then I realized that they're kind of like guilds. Guilds are useless unless players know how to make the best of them, and I think that is the case here. Clubs will only really be helpful if you're trading in a closed club with online friends or family.