I think that TOS had a lot of good science fiction elements and stories, and also a lot of very poor elements. Part of the problem is that we tend to remember the 5-10 best episodes ('City on the Edge of Forever', etc.) far more than we remember the rest of the show. Personally, if you averaged out everything, TOS would probably be on the mediocre side, but there are a few episodes which are excellent.
But that's the original series. If we look at the later series, have they really improved on TOS? There's a pretty good argument that they haven't. In fact, in a lot of areas they're worse (particularly the overreliance on technobabble). Are they really exploring new areas, new 'What ifs' in a science fiction concept? TNG I think tried, but when thinking upon Voyager and Enterprise, I don't really think they explored any new concepts.
So I'm with Card in his assertion that Trek never really improved from its starting point, especially from a science fiction point of view.
But that's the original series. If we look at the later series, have they really improved on TOS? There's a pretty good argument that they haven't. In fact, in a lot of areas they're worse (particularly the overreliance on technobabble). Are they really exploring new areas, new 'What ifs' in a science fiction concept? TNG I think tried, but when thinking upon Voyager and Enterprise, I don't really think they explored any new concepts.
So I'm with Card in his assertion that Trek never really improved from its starting point, especially from a science fiction point of view.