These shows were shot for 1.33 and composed and released on TV in that format. This is way before our recent spate of HD widescreen shows. The only correct way to present them is 1.33. Any 'widescreen' release would butcher the framing, chopping off a significant chunk of the imagery from the top and bottom of the screen.
You know, I wondered about that when I read it because, as you say, the '91 series was produced before HD widescreen shows began popping up. (Not even the DVDs of recent shows like Buffy are in widescreen.) But then I remembered that you'd mentioned that the DVD transfers were being done from HD masters that were made a few years ago, so I thought that *maybe* it was possible. I suppose I should have realized that it wasn't.
I agree that it will be a total disaster if the framing is butchered (which is one reason why I can't imagine that will happen - one would think the outfit doing the transfers would question that's what Sony really wants). But on a slight upside for those of us who already own the series on VHS, if it turns out that the framing does get butchered, well, at least we won't feel as though our tapes are almost totally obsolete...