Talk to Binney. They contract out everything, and don't even oversee shit well anymore. They have regressed to the USG mean.
The motivations are very similar to startups working outside of larger companies. You get more freedom in work choices and pay scale.
Government also discourages small side projects, especially in the classified world, and particularly discourages them from becoming production. They would far prefer to run a program of record, or pay for (well defined) innovation by third parties.