Actually I believe at the moment the problem is not about multiplayer or not. It's more between PvP and PvE.
The style of Avorion is very good for multiplayer. However similar to other games, multiplayer game play will involve the choice of PvP which will lead to a whole new level of complaints and balance issues.
No one like to see everything they set up get destroyed after a day which has a very high chance to occur in multiplayer game. The insurance system is one thing to counter the total loss of the above situation. But is it really necessary to force ourselves to experience it over and over again? It's a very subjective topic.
For myself, if the Dev want to focus on multiplayer, I'm fine as long as they don't remove the single player game mode.