you know i can definitely understand serif & clips points ,
i dont see paintings that have graff as limting at all , there are so many avenues you can venture with letters alone,,then color added.
i dont see how it is limted if people who do letters primarily like zone, ces and who ever else if they apply the same principal thoughts of balance, design, color and composition. As a matter a fact i have a great deal of respect for writers that focus on the letters on a canvas.
My last thought is that i dont always agree with pushing your self ( the limits ), it is good to a certain point, some of the best works i have seen ,graff or just fine that looks like they are pushing the limits came as a natural timely progression.