Similarly in Elite Dangerous there's a full-scale galaxy (regardless of gameplay use) because David Braben is a big astronomy fan - but the actual designed "exploration" gameplay is mainly in or close to the bubble and doesn't resemble what the [long-range] exploration communities think of as exploration very much. (A lot of the Thargoid Titan content is what I would call exploration, for example, just not Exploration)
Depends on the personal definition, of course: there isn't really a "standard" definition of exploration in real life anyway. However, in ED, a lot of the enduring allure of exploration gameplay was I believe unintended by the original game designers, and never really examined much by the developers either. (Hence the common complaint that they don't understand exploration.) These would be:
1. The feeling and experience of isolation and solitude, and there's also the aspect of journeying together with a group of people: the developers by their own admission didn't expect people to head far for long amounts of time (and were surprised when people made it to Sagittarius A* in the gamma headstart already)
2. The possibility of finding things nobody expected to exist, not even the developers: the unintended outliers made by the Stellar Forge
3. Even if it's something you knew could exist, you wanted one of your own: "yeah, I know there are ringed Earth-like worlds, but I want to find
my ringed Earth-like world". (Don't forget that the First Discovery tags were added to the game after launch.)
4. Lots and lots of photos (again, the developers added the camera tools reactively), and of course...
5. "Showing off my ship in front of a cool thing" (by the way, David Braben said he flies an Asp Explorer in ED)
6. The sights of the galaxy itself. How does it look from the opposite edge? From the center? From above, or below?
Other than the very last one, I don't think they were designed intentionally - they certainly don't look that way. These above either can't be done by sitting in the bubble(s), or can't be done nearly as well as out in the galaxy. But to me at least, it looked like the game was released with a somewhat-rushed Forge and entirely barebones exploration gameplay mechanics (there was time pressure, after all, and this wasn't core gameplay), and the developers were actually quite surprised that so many people engaged already with what was essentially a placeholder to be fleshed out later. Which is of course not what they should have expected. After all, give folks a huge galaxy, which no other game at the time did, and the means to traverse it and to stay out there for long (possibly indefinitely, even), and it should come as absolutely no surprise when some people do exactly that.
Back to motivations a bit: there's also that in the bubble, you always know what you can expect to come across. The one exception to that is whenever developers silently add something new without any hints to it before, but well, that's all over the news five minutes after its discovery, and it's pretty much guaranteed to be Thargoid content anyway. Don't get me wrong, that's fine, and I do like that they aren't an entirely clichéd species... but Thargoid content isn't everyone's cup of tea.
Of course, the things I wrote above aren't everyone's cup of tea either. Most people tend not to put up with the monotony of interstellar travel in ED ("JJJJJJJJ"), or with the grinding of the FSS, or how many systems you need to discover to find rare stuff.
Meanwhile, there are hand-authored puzzles to discover and solve. Whether that's exploration is a matter of personal opinion, but it certainly is intended gameplay. Said puzzles include all the Thargoid and Guardian content, and of course Raxxla. Maybe it was originally just a fun reference in ED at launch, but later on, it certainly became something people were meant to be curious about.
So, finally back to the topic (sorry

): if Raxxla ever gets discovered - or hey, maybe it already has, but the few people who did it so far have all decided to keep it secret from everyone else - and publicly known, then the people who'll care about the discovery will generally be the ones whose gameplay would be affected by it. That of course includes the people whose gameplay is the puzzle solving of Raxxla. Otherwise, to the others, it'll be a curiosity.