And also, based on the description of the bikes as being a bit over-engineered, I'm not sure what sort of price savings there would actually be with Aluminum. After accounting for the difference in materials, the bike might need entirely different solutions to the issues and opportunities encountered with the existing design. (I'm not an engineer... so please feel free to correct me on this). All of that trouble with no guarantee that anyone would actually want an Aluminum version of the bike... because as previously stated, the whole point is Titanium.
I would think that a Steel version would make more sense if you wanted to make a cheaper one. However, I would still argue that the whole point of the bike's popularity is that it is designed from the ground up to be Titanium.