It is too bad that these went down, but yech, sharing binaries or even entire OS images made of open source code... what if you want to change one configuration option or line of code while keeping whatever special modifications were made? What if you want to combine the changes in X fancy ROM with Y? (Never mind that the kernel is GPL.)

I'm not an Android user myself, but I will nevertheless suggest that optimally these things would be distributed as source on GitHub, with a deterministic build system guaranteed to be able to reproduce binaries in the future, and only secondarily as binaries.