I might be the one person on this website who isn't nostalgic for Horizons. I found it the least interesting of the pavilions at Future World 1.0, and its vision of the future was already dated by the end of the 1980s. Maybe if they tied it in more closely to Carousel of Progress (the animatronic fathers in both appear to be the same model), lightened the mood a little, and included better music (should have used the Sherman Brothers!), my opinion would have changed.
If anything, something like Horizons should have occupied the globe of Spaceship Earth, because Horizons had no specific theme beyond "the future". Hence, it would have served as a better introduction to the park than a ride about the history of communication. Instead, plopping it in a far corner of the land made its general theme of "the future" appear redundant.
...although, in retrospect, the light-speed progression of communications technologies has been the defining feature of the time period between Epcot's opening and the present day. So maybe Spaceship Earth as we have it was a prescient choice after all to introduce the park.