This game aims to make players play together, form communities and achieve great things.. to-ge-ther. This is not a game for people who play single player, or generally people who are not very social. Especially in the MMO.. sure you can survive without teaming but never will there be any way to build a castle by yourself.
Now, I know what you might think "We want it for YO", well, remember, the devs have got little time for the huge amount of stuff they will / should change / add that is a lot more important than single player mode (combat, skills, buildings..), so they wouldn't have time for that. You can try to mod in a few things for a better single player experience tho, but still I don't see the point playing this in solo tho.