I guess it has more to do with how its been beaten into fans heads that these post-Jedi books were meant to be THE official post-jedi cannon.
I totally missed that memo. Any such "understanding" was always contingent on there being no films set after ROTJ, right? It's not like there was always only one answer to the question of whether any such films were coming, even while Lucas was at the helm. And GL was known to change his mind....
By the way, just for my future reference, is this thread for discussing any SF&F we are reading, or only Trek Lit?