The normal procedure of clicking on a folder result in redirecting the existing file management window to the new directory is the only functional way to operate. The behavior of creating a new window per directory inevitably creates too many window management tasks in terms of constantly closing extra windows.

Also what size your file manager should be is a function of what else you have on the screen which is inevitably variable so you end up resizing and moving windows to fit in with an arrangement that is different than last time you opened that directory. It's vastly easier if you want 2 directories shown side by side is to just use the traditional split view.

The fact that size and position are arbitrarily chosen even if they are per directory means that there is no mental map between position and position in the filesystem hierarchy.

Spatial browsing is a poor metaphor based on nothing that never made any sense whatsoever.