Find files is certainly useful for coding, not so much exploring. I would have no idea what to search for when exploring a new repo. Besides, even when coding with IDEs with find-files feature, I mostly navigate using the tree. Guess I like tree view :).

I use 't' all the time to look up files as well.

I guess this extension makes it easier to get an overview of the directory structure, but that's something I rarely need.

I'm sceptical of browser plugins in general. There are so many browser plugins that change under the hood and do malicious things. It would be easy for the author of this plugin to scrape all your source code and phone it home.