What I want to say is that transparent negative film is an invention that follows the opaque bases for negatives, metal or paper. Even the first flexible photographic roll film made by Eastman Kodak in 1885, was actually coated on paper.
The need of transparent bases for the negative was primarily to allow reproduction by the same methode used for the negative. A paper negative, due to the structure of the paper, gives worst positives than those made with a transparent support. This is more or less obvious. What is difficult to understand is that film remained a standard until today, even tought that the reproduction techniques such as normal scanners are not conceived to give good and fast reproductions of a transparency. They can reproduce paper prints and daguerreotypes much better than transparencies.
The photos below were made with a bellows camera made by my self, using a lens from a cheap binocular, on Ilford paper, Multigrade IV brilliant. Exposisions between 10 and 30 seconds at a 20 W fluorescent light at home. No shutter, just a cover which is removed and placed back manually.
The paper has some advantages over film. It is less delicate, can be handled without extreme care. It does not attract dust as easily as film. It is also more resistent and can be archived in shoeboxes or in albuns. I think that it would be a great thing if some manufacturer offers 'paper film' at least in medium format. The paper should be thinner than the regular photo paper and can do more photos than the film because it will consist on just paper and not paper + film like the 120 rolls.