Small file open and save dialogs

It occurred to me this afternoon while driving home from discussing my broken brain with the general practitioner. Why are file open and save dialogs so small? Screen resolutions have gone up, but the size of these windows haven’t. Often I find myself poking around in a tiny little hole into the filesystem trying to find what I want. Why can they resize to say 80% of the size of the screen automatically?

This complain applies to applications on Windows, Linux, and MacOS equally.