File system explorers need to support a grid view

I was reading about Kanban Boards the other day and it struck me, again, why do all file system explorers -- Finder on Mac OS X, Windows Explorer on Windows, Nautilus on Linux, etc -- only show either lists or trees of the contents. What I want, and want fairly often, is grid views.

In the KanBan example, let's say I have tasks A through N where each task is a file containing the details of the task. (In Agile software development the detail would be the story.) Tasks A-C are yet to be worked on and are in the "To Do" folder. Tasks D-G are in progress and are in the "Doing" folder. And Task H-N are done and are in the "Done" folder. A KanBan Windows Explorer might look like this sketch. The folder's grid layout would be configured via a simple control much like the multi-page print control used in most spreadsheet application's print dialog window.

I think most people tend to have organization folders each with several sub-folders that's contents are of roughly equal importance. For example, I will have a client organizational folder that contains folders for time-sheets, invoices, legal, and specific projects. A specific project folder is itself an organizational folder that contains client resources, external resources, and project resources. I want all these organizational folders to have their sub-folder's laid out in a single row grid. Having grids in the file system explorer gives me a powerful and simple means or visually organize my work without have to learn and use yet another application for an enhancement.