Most of the windows-based programmers I interact with don't know powershell any better than I do. They use GUI tools for interacting with git and the filesystem.
So for me, git bash for git and filesystem interaction is a superpower in these places.
I could learn powershell, and I'm pretty sure it's much better than bash for scripting, but I'm almost never really scripting in bash anyway, I use tools like F# for that. Powershell seems fine, but it's less well supported on Linux and I don't really need a shell based language.
So in the end, git bash keeps on working and I can focus my learning elsewhere. It's stable, still works the same way 15+ years later, so no need to change.