I believe I have read plenty of places either in one of the f.a.q.s or from the main site that many things will require you to cooperate and work with other people. I also remember something about if you do not want to work with others you should go play NWN, this is not me saying this this is just what I remember it saying.
So my guess is that you will probably have to work with others. If your character is a loner it will probably be fine but to be able to accomplish something they will probably have to have some help. This does not mean you have to always have someone with you.
The reason I think they are doing this is so that the game is more realistic (you would not be able to vanquish a nest of ghouls by yourself in rl

) and to help build a community thats members are relient on each other, so that the community is stronger.