I was actually too much used to it and I had a hard time using my friends computer at all using the default Windows explorer.
I probably updated to WinXP at some point and didn't reinstall it. Never felt the need to to install a double windows file manager since then. Even if it's clearly better than the default option.
There is still a ton of weird Windows utilities being developed and maintained. While I personally don't like the platforms, there is a lot of safety in knowing that you can learn a tool and then almost 30 years later, it's still available.
I'm still confident that if you want to future-proof your application, C++ and Windows is the platform to go for. Even if I don't like it.
There's room for improvement (new features are always nice), sure, but 'almost unusable' is quite the exaggeration when you consider that there is ~1B Windows installs and yet outside of small tech circles I've never once heard someone complain about Explorer or its usability.
It Just Works, pretty much all the time, and is easy enough and intuitive enough that I haven't even had to explain it to the tech-illiterates in my circle.
Does the Downloads folder really make you say 'this is unusable'?