Well yes, technically many could, but they are not in EPCOT.
We can agree to disagree, I don't understand the dire need by some to pigeon hole things into very neat packages. You even admit they use some reality based ideas to get to fantastical ideas - GotG is just getting that much more. IMO.
I will add, isn't Tomorrow land when it was originally developed doing the same thing?
Its a very fun ride, and it for all the issues with current roller coasters at WDW is incredibly fun and smooth.
I will add you have to get your past views of EPCOT out of the reality of Today. EPCOT is NOT focusing on real world. It is focusing on many things, not the least of which with Discovery is what COULD be our future as opposed to what was.
I agree the original Tomorrowland would have suffered a similar fate. The redo into the Buck Rogers version actually solved that and created the storyline where Alien Encounter, Timekeeper, etc. (and the story Guardians uses in Epcot) all worked very, very well together. They have since abandoned it into the thematic mess it is today.
Back to Guardians, we should separate the ride from the story. Save for the big blue box, which offends for a totally different reason, I don't disagree on the ride itself. It's a great physical ride. It's got some very cool gimmicks. The music adds a lot for both enjoyment and nostalgia. I'm focused solely on fit of the story chosen. (Just so I'm clear where we agree and disagree.)
For Epcot's story, I'm not sure I follow. How is Guardians focused on the future that could be? It's set today, not in the future. It's at best an alternative timeline in the MCU, not a look at any possible future.
I think you highlighted one key part where we agree - we simply disagree what it means. Epcot is not focused on many things. Some of it is sci fi, some of it is old Epcot, some of it is real world, some of it is a blend. That's the issue. It lacks consistency, and the park was (at one time) the most thematically consistent of any park in the world. I have no issue with it transitioning, but it should still have a consistent overarching theme. As I've said before, if World Discovery was Guardians, Play (rethemed to a fantasy planetary theme) and Mission:Space, with the story focused on our reality and fantasy of space travel, I could get behind that. (Don't love it, but it works.) It's the abandonment for loose ideas like "Discovery" where they are where they lose me. Especially where they are being draconian in single IP lands.
If World Discovery was a series of 4 films billed as related to each other, it would likely fail miserably or feel quite shoehorned. I guess I hold the same standard for storytelling in the parks.