I think it may have been short-sighted not to do a 16:9 version while restoring the series. Full-frame TV shows will likely be broadcast rarely in the 16:9 era once the majority of content is 16:9. Much like Black&White content was rarely shown in the Color TV era.
While I'm firmly in the 4:3 camp since that's how it was produced.
We all know people just want things to fill their screen, that's why most movies on cable are cropped to 16:9, and why Friends and Seinfeld when prepared for HD a few years back got 16:9 versions.
We don't know for sure that there aren't 16:9 versions being quietly made, or at least planned for. Back when TOS was remastered in 2006 they made 16:9 versions (live action cropped to 16:9 with new VFX rendered natively 16:9) for potential markets where widescreen TV penetration was higher at the time such as Japan. Apparently it did indeed air in Japan that way.