Hmmm...a couple of things. You can already be exposed to new areas if you play around with the tab settings on landing page. You can also see what some members have posted by looking at their profiles, if they have made their history public.
That said, I think that being topic oriented is a good thing. Regardless of the technical work it might require, it's a design choice. I think it should be given a chance. Providing members a way around it could ultimately undermine the whole concept. Cake should resist becoming anything other than Cake.