I'm afraid sir that we cannot be friends
No seriously though, they addressed this at the time of the release. They found that only about 90% would not use a multiplayer mode, which would take up a whole lot of development resources and require some design changes to make happen. So they said screw it, and just focused everything into the single player game. Even still the multiplayer proponents are always extremely vocal when something doesn't have it. Even reviewers, they'll give the game an excellent review ticking off numerous highlights, but then end with a 'but where's the multiplayer?' parting shot. And people wonder why developers feel the need to cram multiplayer into everything, whether it belongs or not.
I mean it's not like these are FPS games, where you finish the 4-20 hour campaign then get extended value out of online multiplayer. with the 4x genre you can get hundreds of hours just playing the standard game without ever having to go online. And this is how the vast majority of the audience play actually games like Galactic Civilization, Civilization, Total War, etc.
So Stardock deciding not to include multiplayer in GC2 is a big plus in my book.