I think the truth is in the middle... It does seem as if VP is more a do-my-own-thing kind of lady, and not everybody wants to relive, especially on video, their entire DALLAS experience forever. And that's fine.
But she does have a rep. She "didn't have the best relationship" with the original DALLAS producers according to one prime source, she felt violated by nuDALLAS pimping her character's name and possible existence that VP indignantly went public with her sense of exploitation, she refused to tell Valerie Bertinelli she was fat when an endorsement deal fell through (!), and while I initially thought the female posters here were just being "silly women" when they insisted that VP's and Miss Gray's body language at the 2004 Reunion revealed they were mad at each other, when I later went to re-watch the special, I quickly realized they were totally right!
So someone's apparently not that good at working and playing well with others, and probably has no interest at being so.