I think towny's post illustrates another aspect of this. Namely that the various series have been around long enough for people to think of it as slightly 'real'.
I entirely take the point regarding inconsistencies in plot & timeline, but I find I enjoy Enterprise a lot more if I 'suspend disbelief' and view it as a standalone series.
I have to admit initially I made the inevitable comparisons with previous series and frankly didn't like Enterprise, however, lately I have found the episodes are edgy & entertaining. (with the caveat above)
As to where it goes - apparently only 10 episodes of a new season of Enterprise have been sanctioned, so it looks like 'Star Trek' will peter out
