/Viewport is not a thing until the end of Luclin
 

http://web.archive.org/web/200309301.../20020724.html

The same patch also added the pet window (hence why I put it in green 'bugs').

Neither did broad uptake of widescreen flat monitors.

You could argue using viewport to restrict the view is actually more classic than leaving the command out and having the game played in a super widescreen mode.

This exactly. Viewport allows UI elements to be placed outside of the worldview, which is how it was laid out in the classic UI.

Stated differently, viewport is required because we don't have access to the classic UI.

I didn't even know about this..this may fix my issues with the non classic.ui currently forced.

The best we can do with the UI is to go with the "spirit of classic", because the original UI itself can't be brought back perfectly. If /viewport is to be removed, then a default viewport needs to be forced alongside a UI layout that roughly matches what was in classic.

If that isn't possible then it would be even less "spirit of classic" to remove /viewport.