I doubt it's a dream. You don't let the future profits of one of your studio's most lucrative properties degrade due to negligence.
First of all, respectfully, LOL.
Second, your supporting statement in your original post is only half right. Yes, "They knew the cash-cow possibilities of Star Trek
by 1987." Then again, they also knew apparent cash cows sometimes turn into money pits. As for, "they'd want to preserve that material for future use" you are ascribing predictive powers to these people which goes well beyond what they could have been expected to anticipate at the time.
When TNG was on the air the post-series game plan was syndication, spin-off series, merchandising, video sales, and movies. At the time, 480p was the standard and these episodes were created for televisions of the time. From their point of view, the final episodes (which were edited on video) were the finished product - and they were right; they were and still are the finished product. Their main concern would have been to preserve the video, which they did.
It is ridiculous to assume that they did or should have known that they would need to preserve ALL of the original film elements of the show so that twenty years later they could be reprocessed, reedited, and given new FX shots to meet a standard which did not exist at the time.