Yes but if DSN was shot for Widescreen why not release it in that aspect ratio?
It wasn't. This has been stated over and over again. The last few seasons were possibly*
shot with 16x9 protection, which is not the same thing.
*Coming from someone who has other facts wrong. Plus the fact that "protected" shows are frequently no such thing. Friends and Buffy are good examples of shows that were supposedly 16x9 safe but the various directors still shot for 4x3 only.