Agreed, I mainly play MMO's, because the thing with MMO's is, even if you never see another player, you know everyone is sharing the same world (galaxy in the case of ED of course) and discoveries made by the player are discoveries shared with everyone. You can't have a first discovered/mapped tag in a single player game because essentially everyone is the first discoverer, and at the very same time no-one is the first discoverer.
In single player games the gameplay is the key to the game, in MMO's the world (galaxy) is the key to the game. Ok sure gameplay is important, but in single player games it's the most important thing. Doesn't matter what the world is like, if the gameplay is poor/bad the game will fail. But as we see with SC, somehow you can have poor to non-existent gameplay in an MMO and people will still play it and defend it like anything. The same with ED, a lot of people complain about the missions, some being broken, not enough variety, and in some cases I agree, but people still play it for thousands of hours.