I think much of the technology/personal items were taken when the crew was rescued. At least, the stuff that was salvageable.
With Veridian IV being populated, albeit by a pre-industrial society, I'd imagine the Prime Directive would stat that Veridian III had to be scrubbed by Federation crews. Being that the inhabitants of Veridian IV could possibly visit Veridian III before developing warp technology, I'm sure Star Fleet would want to avoid the possibility that someone could come and reverse engineer the technology in the saucer (granted, unless they could somehow activate a computer, they wouldn't discover warp drive from the saucer, they could, conceivable figure out replicator, holodeck, etc. technology with a look around), or at the very least they'd know that other races existed.
It's been years since I've read them, but I want to say some non-canon answers might be found in the Trek
books The Return
(part of the series of books, beginning with Ashes of Eden
that William Shatner co-wrote with Garfield and Judith Reeves-Stevens), Imazdi: Triangle
(which, if memory serves, started focusing on the TNG
crew on Veridian III ready to be taken away by the ships sent to rescue them), and, I can't remember if Rogue Saucer
had a scene addressing it (I'm thinking not, but since the plot, which took place prior to Generations
, centers around a saucer section that could conceivably land on a planet and take off again, it's a possibility it had a scene on Veridian III).