1) Very few indeed. 2) I will say mostly bad, but this is also a factor of his personal ability to cope financially and support bash at the same time. But again, mostly bad. 3) ahmmm not always. You can make the argument the linux kernel is very mature but the maintenance cost isn't low at all since it needs to keeo changing and is also getting larger and larger. 4) Yes agreed, but sometimes this isn't an option because many companies want to build propriatery solutions (for reasons that may be valid or not). If I am a developer at that project... well I will reuse as more mature code as possible, but then I'll need to write new code as well