You seem to be under the impression that the only reason people consume open source projects is because they want the source code. For many use cases, they are simply consumers of applications, not developers. Google Code tries to satisfy both user groups (this is why all the project homepages are in a consistent format, downloads are easily accessible, developers don't have to learn markup to host docs, etc).

While Google Code has some work to do on DVCS features, I still find it far more generally usable and thoughtfully designed than GitHub.