I don't get the nostalgia for the original EPCOT. I had been there a handful of times pre-1995 (pre-teen years) and then not again until 2009+ (well into adulthood), and I found the latter visits to be far superior.
Soarin'? Compared to the Cabaret and the other thing that either preceded or replaced it? C'mon. Original EPCOT + The Land = Solely the boat ride. Substantial gain.
Mission: Space? I have vivid memories of my childhood, but one of them is not Horizons. I would have remembered something about it if there was something worth remembering. Substantial gain.
Test Track? Ok, the original version was better than the computer version, but the computer version still stands on its own as a great ride. But like Horizons, I have no childhood memory of World of Motion...Couldn't have been worth remembering. Substantial gain.
The Universe of Energy (even pre-Ellen and BNTSG)...Fancy moving auditorium seating and some dinosaurs. That was nap time. No big loss.
The Wonders of Life...Ok, the loss of Body Wars was a substantial loss.
The Living Seas...Ok, a de-theming from Nemo and a return of the Hydrolators would be welcome. But otherwise, it still largely is what it is.
Journey Into Imagination...Ehh, Figment is still Figment, Honey I Shrunk The Audience was cool, seeing Captain EO again was cool, but I really don't mourn either of their losses. The jumping fountains are still the best part.
Spaceship Earth is still Spaceship Earth.
Everything not around the perimeter of Future World (with the exception of Spaceship Earth) was, and still is, a complete dead (to me) zone and is inconveniently large when crossing.
The World Showcase...Other than the conversion from Maelstrom, I can't think of anything else that isn't substantially the same as it always was.
Summing up the substantial gains/losses:
+3 (Soarin', Mission: Space, Test Track)
-1 (Body Wars)
I'm just not seeing the nostalgia.
Nothing wrong with your opinion, I just disagree completely. I'll go pavilion by pavilion with my thoughts:
The original Imagination was one of the best rides Disney has ever built; the current incarnation is one of the worst. ImageWorks was also incredibly fun for kids and it's not even close to what it once was. That pavilion has taken a major hit.
Horizons was also one of the best rides Disney has ever built. Mission: Space is okay, but nothing special. Another giant loss there.
World of Motion was a great ride. Test Track 1.0 was a good ride too, and was better than Test Track 2.0, so... net loss even just comparing the original Test Track to the current version.
The current incarnation of Spaceship Earth is worse than the older version in several ways, so that's another loss.
As you said, the entire Wonders of Life pavilion is gone, so that's a loss by default.
The Living Seas was much better back then as well -- not only because the Nemo ride is awful and took away your ride through the aquarium, but because the whole theming of the pavilion as an underwater sea base was really well done. The first time I was in EPCOT as a young child I actually believed we'd traveled under the ocean because of how seamless and integrated the entire experience was from start to finish.
The Land is the only pavilion where I agree with you. I think Soarin' is a net gain for that pavilion over the two former shows, although I think it's a bit of a stretch thematically. Even there, the interior of the pavilion overall is not what it once was when it had a fountain and other touches that have been removed, but I don't really blame Disney for that -- I don't think there was enough space for the crowds as attendance increased.
I personally really liked Universe of Energy; the theater moving into the past and seeing dinosaurs was incredibly cool as a kid. It wasn't on the level of Imagination, Horizons, Spaceship Earth, etc. but it was a good experience. Guardians could be a better ride, but it also doesn't fit the park at all, so it's hard to say it's going to be an improvement. It's also not open yet so who knows.
I would say every single pavilion in Future World is worse, and often significantly worse, than what was there in, say, 1994 except for the Land. It's basically a skeleton of what once existed. With that said, some of those rides would have needed serious changes/updates to still exist today. Horizons would have needed a complete overhaul, for one. But that would have been preferable to replacing it with Mission: Space.
Just because you don't think Horizons and World of Motion were worth remembering doesn't mean they weren't for other people -- Horizons absolutely blew me away as a kid. I almost never watch ride videos on Youtube, but I've watched Horizons several times over the years because of how much I miss it. It, Journey into Imagination, Spaceship Earth, and the original Living Seas are what made EPCOT my favorite place in the world.
As for the World Showcase, yeah, it's mostly the same just walking around and looking at it. I think the change from Maelstrom to FEA was a loss for the thematic integrity of the World Showcase as a whole -- especially since it also changed other parts of the Norway pavilion to Frozen -- but I don't think FEA is a worse ride (I don't think it's a good ride, but I don't think Maelstrom was especially good either). I do think the food quality in the World Showcase has decreased over the years, but that's an issue across WDW as a whole.
