C'mon on now, I know fans are prisoners of the moment but you don't remember 4 fights ago when he took on Griffin right after
Griffin lost the title. He then decided that he was to good of a friend to Machida to fight for the title.
Jake Shields is on the P4P list because he is a WW who had a win streak in that weight class who moved up to MW and won some fights and a title. BJ was on the P4P list because he was a LW who moved up to WW and won the title. GSP fought a smaller guy moving up in a super fight. Now that he doesn't have the advantage of being the naturally bigger guy in the super fight he waffles and wants a catchweight.
Andy won't fight Machida because they are close friends and stablemates and I don't remember Rashad ever being offered to him. The UFC doesn't want to use Andy at 205 unless he is staying there because him wrecking contenders would **** up the division. Which is why Dana wants GSP to move up to 185, challenge for the belt, and stay there. The UFC doesn't have a super fight model they want guys to pick a division. Andy is really the only guy who has bounced to another weight class won and not stayed there that I can remember.
Shields has beaten Okami, Miller, Lawler and Henderson, he also has the longest win streak(2,500 days) of anyone else on that list and if he beats GSP he's likely going to break Fedor's record of 3,500 days without a loss.
BJ was on the list because he held titles in both classes and was the only LW in consideration for the p4p list.
You also forgot Jon Fitch who's on the list.
As for fighters who didn't stick in weight classes that they were winning in IIRC Vera 8-2, Sanchez went 2-1, Belfort...5 or 6 and 1 before the catch weights and middleweight fights.