Why adapt Frankenstein or Who Censored Roger Rabbit?
I freely admit that I haven't read
Frankenstein, and that the only adaptations I have any experience with are the two (a movie and a stage musical) about Victor's grandson, Frederick, a pop-eyed assistant with a strangely mobile hump on his back, and a zipper-necked monster with an enormous schwanzstucker. Oh, yes, and those versions have a happy ending.
As to
Who Censored Roger Rabbit, well, I
have read that, and according to everything I've read
about it, Gary Wolf liked Disney's version so much better than his own that he wrote sequels to it, and formally deprecated his own original. And I don't blame him one bit for doing so.
As to what you
didn't mention, i.e., my favorite target of derision among all film adaptations of speculative fiction, I maintain that MGM's ham-handed monkeying with Baum's most famous opus was a mix of pointless changes for the sake of Technicolor appeal, and intentional dumbing-down of the whole premise of the story. And I wouldn't be nearly so pissed about it if it didn't create a "tail-wagging-the-dog" situation.
But
Star Trek doesn't (with the exception of the Abramsverse) generally involve reboots or reinterpretations of prior works. It's one big happy (albeit far from seamless) continuity. This was particularly true of the long-running Novelverse that was brought to a heroic end not all that long ago, to make room for PIC, but really, even at the peak of Richard Arnold's reign of terror, it was still a single continuity.
In the case of Una's Illyrian heritage, of course it had to be retconned as something that was kept quiet, in order to harmonize it with the Federation-wide Augment-phobia that was established in DS9:"Dr. Bashir, I Presume" as continuing into the TNG/DS9/VOY era. (I will note that Jenniver Aristeides, from Vonda's
The Entropy Effect would have a much more difficult time being so harmonized!) But really, having just read every bit of prose TrekLit involving Una (except the NF novels that don't
quite openly declare that she's Morgan Primus), I can safely say that the discontinuities with Una aren't really any worse than the ones that had started appearing in
canon ST since before Rand was written out.
The main story of the Legacies trilogy has to have happened
before the main story of
Crisis on Centaurus: after the very first chapter of
Crisis, most of New Athens was a glassy, radioactive, crater. And yet Legacies somehow
feels like it happened
after Crisis.
At any rate, most of the continuity problems that kind of jumped out at me were things that seemed as pointless as the proverbial "ruby slippers" of the MGM Oz, e.g., what story point could possibly have been served by Joanna being raised by her mother and estranged from her father, with no trace of Ferguson's easy "Hiya Squirt"/"You big mushball, don't get sloppy on me" familiarity?