Putting in widescreen would completely change the show, completely change the composition of shots, the framing and even reveal elements of production in the case of how TNG was filmed.
But, go ahead, compare apples and oranges.
As Maxwell Everett
has shown, you can crop the show and none of the production elements would be any more visible than they were in the 4:3 presentation.
It's not an apples and oranges comparison. You've decided it's okay to change one persons work so it is more enjoyable with modern technology but are completely against doing the same thing with another persons work because you disagree with the change. The audio tracks were built to be listened to with the equipment of the time, just like the video was done with a certain way of viewing in mind (nevermind that with overscan we are already seeing the picture in a way that wasn't intended).
I've never seen people who are convinced allowing viewers to make their own choices is a bad thing and to be avoided at all costs.
Many disks do offer original mono tracks as an option, probably with preserving the original experience in mind. However, since mono movie soundtracks were often mixed down from stereo you're not really messing with anybody's original intent there, are you?
This is all apples & oranges. It is only the persimmons (the 4:3 shows that protected for 16:9 I mention above) that can resolve without distorting creative intent. And if viewers can't perceive that (let alone respect it), then they're demonstrating a crucial blindness about what it is they supposedly cherish.