>But I suspect the real reason Microsoft has kept this default over the years is that it prevents users from accidentally breaking the file association when they rename the file.
I doubt it. There's already enough preventative measures if you have "view file extensions" enabled. If you try to rename a file, only the part before the extension would get highlighted, and if you try to change the extension you get a scary warning.
As far as I remember, those preventive measures were not in place back when hiding file extensions was introduced, which was either in 2001 with Windows XP or perhaps even earlier.
I doubt it. There's already enough preventative measures if you have "view file extensions" enabled. If you try to rename a file, only the part before the extension would get highlighted, and if you try to change the extension you get a scary warning.