At the time, memories of the debacle that was Pam's Dream were fresh -- it had even become a punchline for several sitcoms. And the exit of Pam was karmically connected to Bobby's clunky resurrection in the minds of the viewer, so the producers tried to sweep Pam under the rug as swiftly as her car swept under that propane tanker, using Bobby's "pain" over being dumped yet again to justify the show all-but-ignoring her absence.
They even called one episode "The Mummy's Revenge" --- well, just who is the mummy?? It's Pam -- it's Victoria Principal!
So Katzman was clearly cognizant of the fact that Pam, who started out (for about 5 seconds) to be the star of the show, had been disrespected in certain ways... Yes, JR's ascendency was important and necessary. But when Pam later went to work at Ewing Oil, the writers sidelined her and muffled the storyline, and
then she was pushed further out of the way with Bobby's foolishly executed (or un-executed) return.
And then they push her semi-dead body even further out of the way once she exits by having everybody ignore that the character was ever there in the first place!
So, yeah, if Katzman thought Principal had been screwed over (and largely
by him) then who's to argue the point? But he seemed to have an all-male psychology about DALLAS (which the closing years indicated most vividly). And while I would never suggest that DALLAS should ever be some kind of feminist document, Katzman just seemed overtly biased in the other direction.
David Jacobs also admitted that Victoria didn't have the best relationship with the executives, and that that likely fed into how Pam was treated, and her exodus handled so shabbily.
Also, in anticipation of an upcoming writers' strike in 1987 (which was actually delayed by a year) Katzman and the Lorimar chose to forego the usual spring hiatus period when the writers plan and structure the upcoming season, and instead went right into shooting the next year -- so they had to write while they filmed. Which is partly why the pacing is a bit off for the 11the (87-88) season.
I still say that tanker truck Pam crashed into should have been revealed to be doing illegal business for JR... It just
had to happen.