Well, there is longstanding bad blood between Palladium and WotC over a very early product (early 90's, predating Magic: The Gathering) called The Primal Order. It was meant to be a generic, intersystem sourcebook on playing gods. It included a conversion for the Palladium system in it (among conversions to other systems), which got Palladium suing WotC, and later settling. Notice that WotC still exists and is bigger than ever after that, and they were selling Primal Order after the settlement.
Also, Palladium books is run by one man: Kevin Sembieda. When you say "Palladium books likes/dislikes. . ." you really mean "Kevin Sembieda likes/dislikes". He makes all the decisions, and he created the entire system and it's settings. The Palladium system is essentially his personal homebrew rip-off of 1st Edition AD&D mixed with a percentile skill system and a few other ideas. Saying you want a d20 version means you don't want the version of his personal, private system and he takes that as a personal insult. He's quite happy with his system as far as he's concerned, you should be too.
They also seem to not understand the concept of the OGL, and are deathly afraid that if they make a d20/OGL version of their game (or permit others to, even fans doing so informally) then WotC owns all their intellectual property. To him, fans who try and produce a d20 conversion of the game to share with others aren't fans, they are ungrateful copyright thieves who are bastardizing the game, and fans who just ask for a d20 version are merely sheep who are on the "d20 bandwagon" and are ignoring his "good, proven" system for the "fad" of d20.
Palladium used to have a reputation of being good to it's fans, but it also has a reputation of being the most heavy-handed company in the entire RPG business when it comes to anything smelling of IP law. I doubt any other company in the industry would go to the trouble of sending Cease & Desist letters to fans on an internet mailing list discussing how to convert their product into another system, for example. Admittedly TSR in the "bad old days" did do things like send small-press magazines Cease & Desist letters for merely mentioning AD&D in their articles and columns and threatening fans who put up a homebrew spell or character class on their web pages, but look where that attitude got TSR.