I just wanted to add my support for this kind of system.
As Construct doesn�t seem to have any kind of patch system for bug-patching finished projects (correct me if I�m wrong) it would be smart to keep the .exe file size as low as possible to reduce download-time for users. At the same time, I would rather not have all graphics spread out in folders, I want them to feel safe in a file somewhere.
Also, it would be great if you could have "families" for your graphics, so that at a layout start up you could tell the game to load a certain family file, and all it�s graphics gets loaded, like, you know, "load snowy landscape tileset" and such.
Basically, you import you graphics, give it a family name, a file is created which stores every graphics of that family in that file, and then you would load the family at layout start up. Wouldn�t that be handy?