I don't totally disagree.. sort of I guess I do.
We maintain directory structures under userpics based on userid, I don't see the difference maintaining a structure in albums.
Also Coppermine IS an excellent front end for creating collections of images. But if the images all end up in one directory it makes it much more difficult than it needs to be to use those images for anything else. IE: maybe you just want to burn a set of categories to CD.
There ARE other problems with maintaining alb/cat structure, like legal directory structures that are illegal in coppermines cat/alb structure. However any coppermine cat/alb structure can be emulated on disk, and that organization and ability to collect add and move images around could be harnessed and used for other purposes than just displaying images to John Q. Public.
I don't think we should entirely dismiss the idea. However I don't think it should be discussed for 1.5. I think this would be a 2.0 discussion.