I never really bothered with the multiplayer mode in it - I know the game was built with a multiplayer back end, but they did promise a single player mode, and they do present the game as having a single player/solo mode.

Obviously different things annoy different people, and I do get what you mean about quitting and restarting etc, but it was enough for me to stop bothering to play it and play X4:Foundations instead. I did still get over a hundred hours play out of it, so I don't exactly feel hard done by, but if quitting to the main menu works, then it's clearly mechanically possible for them to let you pause it, they just didn't want to.