Just a few points.
The only real reason I have problems with a remaster is due to the extremely poor fx work that occurred in TOSr. I just can't really express in words how disappointed I was with about 80% of the space scenes.
Ok on to the positive. Well teh great thing about the TOSr is that it didn't replace the old. It produced both. If you liked the original, by god you could watch the original (just with a better image). Kudos for that.
On teh issue of well since the actors were filmed on film, then we can certainly go back and restore the film quality and just not replace the special effects.
And while you could do this, it would be an extremely unwise choice.
1. The reason most have this view is to only use the best quality of the materials at hand, but not to change anything. But unfortunately TNG, far, far more then TOS incorporated fx with live shots. That means material that was composited with video resolution so that fx and live action would looked balanced would no longer occur. You would have a pristine live action plat and poor visual plate that can't be improved upon. Leaving a jarring composition.
Myself I am more comfortable with a fairly faithful recreation of the FX at hand. But with several conditions.
1. Please reuse ships that have every logical story reason to be in that episode, but please, please fix the scale of those ships. Please.
2. For the most part I think originally design space shots should be recreated (though they can be cleaned up) but for stock shots, I have no problem with new shots of a similar nature being used.
3. Shots where recycled ships have no rational reason for being there (two different alien ships using the same design) I have no real problem with new designs being used.
4. I also have no problem with new details being used on ships that were rushed. See for example the new Ambassador class details and new stargazer details that the original designers have come up with in fairly recent years.
5. I have no problem with new design being used in shots that they would make perfect sense to be in. Take the shot in Redemption part two where the Enterprise is part of a large fleet, but the exterior shot we see is three vessels (A nebula, an ambassador, ect), since we know there are many other ships there they could easily show another.
Or even a shot (this happened on ENT) where due to the effects crew being completely swamped with the Pilot, they had no choice but to reuse the Motion Picture Klingon Cruiser, even they they absolutely did not want to.
6. Correcting errors that the production made. IN Darmok (and I love the quality of the shot, so thats not the issue, in fact I love the effects work on that episode) but clearly they made an error with phasers coming from the photon torpedo tube.