This topic has spun thru my head many times, too, but I always come back to the simplest explanation. Its just the way people are: prone to mistakes, slow to correct them, and awkward in execution. (Page/Plant) Further, people are usually easier to offend than we imagine, and slower to forgive than we hope. (Jones)
When the whole Page/Plant thing got underway, those two would be anxious to get started, but wary about Jone's feelings. (FEELINGS? Oh, no.) So, they drag their feet, hoping to avoid the confrontation. If they call, it might get uncomfortable, emotional. No man wants to deal with that, particularly with a buddy...he'll understand, it'll be fine. It's amazing the things you can convince yourself of in order to get out of an unpleasant task. Then, equally amazing how simple it is to see you were wrong, in hindsight.
Then, it the midst of everything, some reporter has to throw a wrench (spanner) in things. Quick, a joke! "He's parking the car." (See? We didn't forget him, we're still mate's, nothing to worry about) I'm certainly not above falling in to that bad decision. I'm also sure that had I been JPJ sitting at home watching my bandmates re-take the throne without me that I'd have been mad, hurt, and felt slighted and mistreated.