Not sure what you mean specifically, but here's some of my thoughts (note that these do not represent those of the product team)... * Technical reasons. All ca

Not sure what you mean specifically, but here's some of my thoughts (note that these do not represent those of the product team)... * Technical reasons. All calls to Android Maps API happen via an IPC (inter-process, not intra-process, actually), so they are generally slow. That could be bad for things that should be fast to compute like everything in SphericalUtil and PolyUtil. * It's hard to design a nice API for Clustering. Having it open-source means Google doesn't have to guarantee support for that API according to the ToS (iirc, >1 year) * Open source library code demonstrates use of the API. You could think of it as additional sample code. * There's some value in having open source code, generally. A lot of the stuff could be useful in other settings - for example, you could port a lot of the math code to other languages.