"The Orzhov guild is founded on the beliefs that wealth is power, that structure breeds wealth, and that guilt creates structure. The guild is a combination of a religion, credit-lending agency, and crime syndicate."
... I admit, I like the sound of it. Religion, debt, crime - three things that pretty much get whatever you want. But it seems more like a self-perpetuating machine, an organization that exists solely to continue its own existence. Sure, in terms of concept, it's very me. Offer people exactly what they want, in exchange for their servitude, it's pretty straightforward. But it doesn't seem to go anywhere.
That, I think, is what the Blue element adds. It adds purpose - a goal of seeking, understanding, improving, perfecting. The White adds structure, the Black adds ambition and power, but the Blue adds function.
Also, amusingly enough, in both of the tests I took, Black was lower than the other two. White first, for me, then Blue, with Black coming after. Which makes sense - I appreciate power, but ambition isn't my highest priority.