Yes, that's true, but you've somewhat conveniently picked the polar opposites when considering that argument. There is no reason a coaster couldn't be as diverse as Small World and Pirates. What I was more getting at was Western River Expedition and Pirates. In terms of things that people want broadly. In that case we are talking about two fairly similar experiences in the same park. Even if Epcot built Space Mountain 2.0 (which this isn't per say), I'm not sure if that matters in so far as they are two separate parks.
There seemed less concern with Tron occupying Epcot and that was more overtly built as a Space Mountain replacement.
Particularly when it comes to Epcot, a park somewhat known for a lot of same-y attractions once upon a time. Guardians meaningfully expands the diversity, but it's being down-played that it does not.
I thought Space was once upon a time considered a good attraction? Now Space 2.0 or 3.0 is being thrown around like a bad thing.
I simply picked the first two boat rides that came to mind that happened to be in the same park, illustrating that you can share a ride system in proximity without the rides being accused of being "the same". If you were getting at Pirates and WRE then say that, because there was no way to infer it. But keep in mind, the point with Pirates and WRE was that they were designed to exist exclusively on separate coasts, and one was never actually built largely because the other one was, which makes them somewhat inadmissable to the argument here.
Surely people would speak up if Disney built Phantom Manor at WDW given its many shared elements in The Haunted Mansion. Guests can't ride those attractions in the same trip, though, let alone the same day. But you can bet people will hop parks and catch Cosmic Rewind after riding Space Mountain that morning, or vice versa.
If you reread my post you'll see that I said Cosmic Rewind suggests
in its execution that there's less latitude for difference - which doesn't mean you
can't do anything else with a coaster in a box, because clearly Disney has with other attractions, but rather that it's evidence that Disney has little intention to do differently with this sort of concept. When it comes to coasters in a box to simulate Space Travel they seem to have a language they're comfortable with. Which, like, it's amazing there's even such a sample size to refer to.
For the record, I had issues with the idea of TRON in EPCOT, and this was among them, not that I think that counts for much at this point.
Your point about same-y attractions at EPCOT was my earlier point - that the shared "long-form Animatronic Dark Ride attraction" style offers so many opportunities to create a distinct attraction personality. And at EPCOT Center, they did just that. Famously, in fact. It's not like people confuse Horizons for Universe of Energy. In fact, that's why Cosmic Rewind can make jokes about those things - because even decades later people remember them distinctly.
I don't think people are necessarily using "Space 2.0" as a derogatory term - Space has certainly seen better days, and desperately needs to see them again, but that notwithstanding it's obviously a well regarded classic. The problem is in creating any big, new attraction that too closely seems to copy another one's homework. There's new tech, of course, but as I said, their aesthetic personalities are at many points indistinguishable.