For heaven's sake..Yoda HAD a floating chair in Episode II...he used it while talking with Obi Won at the Jedi temple.
While I see your point, there's a difference between a small, modest, floating chair and a massive, big, fat, red thing with the Imperial ensignia projected above it. It simply looks ridiculous.
P.S. It hardly floats, is flies about the place like a swoop bike - it would have worked a lot better as a meditation chair
which it claims to be.