Here is a reason: You can view the configuration files and logs of a damaged system by mounting its disk in another system and using any old text editor. There is no need to install special tools.
I agree that's the advantage of text formats. Just as that's the advantage of text networking protocols over binary protocols (you can read them with wireshark or even use telnet).
But you have to weigh that advantage over other advantages. If it was this simple, every database (and we are talking about a database here) would just be text to make recovery easier.
I agree that you have to weigh the advantages, but we are talking about a special type of database. Most configuration data is read-only during normal operation. It's not as if anyone stores customer data in /etc or the Windows registry.
Sure, but what if my only Windows system won't boot? I am sure that I can access the registry from a Linux system somehow, but it's not as easy as invoking less or vim. That is especially true if the Linux system doesn't have a GUI. I don't need a GUI to read a text file.
But you have to weigh that advantage over other advantages. If it was this simple, every database (and we are talking about a database here) would just be text to make recovery easier.