Also I'd like to point out that Skynyrd & Kiss didnt reform as they never split.
Yes Kiss went back to older members & make up but to reform they woulda had to have split in the first place,kinda like when Ozzy or Dio rejoined Sabbath!

As bsams said,I dont for a second believe money would have been a motivation for a Beatles reunion as they had plenty of that,the big stumbling block was John & Paul with Ono making sure the rift was maintained and pushed further!
Both George & Ringo worked with both guys while all four were alive,but John & Paul still maintained their distance.
Paul,George & Ringo worked together on Free as a bird over Lennons vocals but I'm not so sure Lennon would have done the same had it been Paul who was killed!

I am not saying Ono didnt love John but she did everything she could to keep his feud with Paul alive & since John has died,she has sold off his possessions like they have no sentimental meaning to her at all!