what is the game? what is the rest of the game? what do you want it to do? its just a small pew pew mode... is exploring disjointed from the rest of the game too? are srvs disjointed from the game too? nobody is saying elite is perfect and the ody content can get really far from that definition, but what would you like the joint between the fps and rest of the game to be?
I think the issue is that it's okay for parts of the game not really to relate to each other - other than some minor bits around engineer eligibility, exploring won't improve your combat potential and vice versa, and that's fine and probably for many players desirable - but it's a big problem when it comes to making a paid expansion, that Odyssey has and Horizons didn't.
Horizons' "big thing" was planetary landings. But if you weren't interested in planetary landings for their own sake, there were plenty of places - especially by the time they'd finished it in 2.4 but some even in 2.0 - where going down to planet surfaces would help your normal spaceship flying: that's where all the engineers are, almost all the Guardian and Thargoid sites, plus surface bases came up as targets for standard courier/cargo/passenger missions often enough that not being able to do those limited your choice a bit, and could be profitable sources of trade goods or closer-to-the-star destinations, plus various CGs, plot events, unique sites, etc. were set there.
Odyssey's "big thing" is getting out of the ship. But if you're not interested in that for its own sake, it's all compartmentalised off so you can completely ignore it. You're missing out on some minor convenience of using Apex to optimise ship transfer, some additional surface markets which largely are too small and unpredictable to be important and can't be mission destinations for ship missions [1], and some exploration credit payouts via exobiology. None of the materials you pick up on foot help upgrade your ship, there's no interesting non-procedural sites on thin-atmosphere worlds (things like Dav's Hope, but not even necessarily the materials ones), no surface tourist beacons there for passenger missions to go to or just personal interest, no Guardian and only minor Thargoid presence, no thin-atmo-exclusive trade goods like Horizons surface bases had, no CG hosting.
And that would have been fine if they weren't hoping people would pay for it. The problem is that even now the release performance and bugs have been fixed up to "no worse than the rest of the game", unlike Horizons there's still no real reason for people not into its "one big thing" to buy it.
[1] They are potentially valuable in competitive Political BGS, but the intersection between "people who are into that" and "people who pre-ordered Odyssey" is probably quite tight anyway. It doesn't help to sell it to the much larger number of more casual players needed for commercial success.