Even if you're replacing the software, having the source allows you to ensure that your replacement is fully backwards compatible with the original Same answer

Even if you're replacing the software, having the source allows you to ensure that your replacement is fully backwards compatible with the original Same answer : True in theory, very rarely practical in reality. The only thing that really matters is the spec of the data format used by the program. You can't just blame the Linux community, though. I agree, it's not just that, but it's the main reason. 15 years since the start of KDE and there's still no sign of a unified, viable platform. If there was one, hardware support would follow.