Please do not take this as semantic hair splitting, but a core part of unix philosophy is that everything beyond core functionality is provided by separate applications. (Some of these may be large and feature rich.)

I think what you are asking is that the ability to manage desktop icons be seamlessly integrated into the desktop application.

Nokia seems to have decided that this functionality to too confusing or error prone. They are not alone. See Amazon Kindle forums where users have been loudly and frequently begging for folders for years.

Fortunately for n900 users, only some simple and easy text editing is required. It is almost almost always much faster and much easier and much more portable to develop this sort of application.

Developing a good GUI application takes longer and requires different additional skills, which often means different people. It may be that a great GUI developer does not know the name and format of the files. This is what makes open development communities great. (And, in actuality, fast.)

I am grateful that Matan has provided the necessary information to the community. It is three years and counting for Kindle users, less than a month for n900 users. You are watching discoveries nearly as they happen.