I'm actually not sure how much more noticable the lighter boxes are on the TIE fighters are, compared to the signs of artificiality CGI still leaves. More noticable to me is that the motions of the spaceships were designed for the big screen, so they poke along and seem very crowded together on a TV.

I did notice the effects work improved over the movies, but I think that was somewhat tangental to the actual quality of the films. There's a point where the effects work is "good enough", and the rest has to depend on the writer..