Have you seen the remasters of Hogan's Heroes, Knight Rider, The Equalizer or Charlie's Angels in HDTV? They've all been cropped for 16:9. Only occasionally do you miss the top or the bottom; the mask is floating to get the most information possible.
But, see, that's not really the point.
A) You could argue cropping like that is "changing the director's artistic intent" for the scene/show.
And B) Widescreen isn't about "filling the screen" videophilles prefer OAR (Original Aspect Ratio) TNG wasn't filmed in widescreen so it shouldn't be presented in widescreen.