There is an art to when and when not ride two abreast (i.e. single out in fast traffic etc..- its all been said).
But personally I just ride two abreast 90% of the time. I like to chat to the guy next to me, enjoy the ride, and dont like continously moving in and out as it becomes a chore. Potholes are bad enough to avoid at the moment without trying to sychronise a group of 10 riders to keep changing formation.
It may inconvenience some drivers a small portion of the time, but on balance I am safer.
While on the subject, yesterday a group of 10 of us were slowing up to take the right to the tea stop. Cars parked on the verge either side. Children and families walking along the road (no pavement). Then a complete dck in a Rover decided to floor it past. He got halfway through us before a red car popped up infront over the brow of the hill. Rather than stop, he floored it more. The red car screeched to a halt at the front of the pack, and he pulled in on the front to riders who had to scarper into the grass verge. C0ck!
p.s. if we know a car is waiting we will wait until there is a safe point in the road and if he needs us to single out to get past we will eventually. But it is us who make the call, not some arrogant driver.