> But hey, if the Subversion system just works and doesn’t bother anyone, there’s no reason to make any changes, right? The reality is that there’s an ongoing maintenance cost to any software, and that goes extra for public-facing services on the internet.

This is a poor excuse. I understand that MSFT/Github feels compelled to provide a convincing reason to users, but this is not it. 99.9% of problems are caused by developers making changes or pushing new code. I've been writing software for close to two decades now--if you don't touch it, it's not going to break on its own.