PCGamer has a Q&A session with Relic talking about their recently released RTS game 'Dawn of War', my personal favourite game at the moment.

PCG: <Dolemite791> most RTS games have around 16-20 missions and more than one race. Why such a short campaign and why only one race?

Jonathan Dowdeswell: Basically we really wanted to focus the campaign from the POV of the Blood Ravens. Since the universe wasn't that well known to a lot of people, we wanted to give a really clear introduction, and give people a chance to learn about it, without switching sides.

An interesting read indeed if your'e a fan.