Either they don't want to release it or they can't (a third-party contract/NDA), at least right now. Open sourcing is often seen by big-businesses as potentially "helping" competitors undermine, replicate, sue, make interoperable wares which may threaten the "Golden Goose." It sucks, but that's the situation... lawyers can't force them to release other code unless they're caught TiVoizing some GPL 3 code or something similar.
You'd think Apple would want to invent the next cool kids bandwagon, maybe invite some community goodwill and crowdsource maybe some new features like fixing time synchronization to have a high-precision ability or working on another actual replacement for HFS+, or adding Windows compatibility. Maybe developer pressure could sway them, and wouldn't it be a good PR move to eventually relent after a long, drawn-out public debate which buys some time for the Apple Car or whatever else is cooking next to be readied? Ive and Cook have massive shoes to fill, which they and the Apple team helped fill, but many people don't think that right now, at least not yet.
You'd think Apple would want to invent the next cool kids bandwagon, maybe invite some community goodwill and crowdsource maybe some new features like fixing time synchronization to have a high-precision ability or working on another actual replacement for HFS+, or adding Windows compatibility. Maybe developer pressure could sway them, and wouldn't it be a good PR move to eventually relent after a long, drawn-out public debate which buys some time for the Apple Car or whatever else is cooking next to be readied? Ive and Cook have massive shoes to fill, which they and the Apple team helped fill, but many people don't think that right now, at least not yet.