.... I've not very knowledgeable about the nuances of the 6.0 system, so please (politely) correct me if I'm wrong, but I believe that there was a bigger reward and not much risk for the quad.
I don't know if this was addressed by another poster, but I want to make sure that the facts are known to all. Under 6.0, the quad was *very* high risk for years.
After Urmanov's Olympic victory over Boitano, Cinquanta told judges that, from then on, they should only give credit for elements accomplished, not for more difficult elements attempted that were not completed. After that, skaters tried *very* hard to "skate clean", i.e., without any falls. Falling usually resulted in lowered marks for Presentation, which was the bigger part of the total score. Since the quad itself presented a high likelihood of causing a fall, skaters definitely were raising their risk level by attempting it.
I never liked quads per se, because they appeared to increase the wear and tear on the skaters' bodies. For this reason, I should not like to see quads become mandatory; however, I think that raising the number of points rewarded for quads and quad combinations might be a good step. That would leave the decision up to the skater.