Both are important, of course, and work hand-in-hand with each other, but isn't the real secret to making money with Adsense in getting traffic. I may be wrong in this thinking, but I'm always suprised to 5 to 10 times as many members viewing the Adsense forums versus the single digits for viewing the Marketing forums in order to learn to generate traffic (which in my opinion is a much more valuable topic). It makes me wonder if many members are focused on optimizing for Adsense as their primary source for generating money, when Marketing and getting traffic is the true source for making Adsense work. Just my opinion.
Marketing doesn't have 10 billion people crying about lower earnings. Marketing doesn't have 10 billion people balling about geting banned! Marketing doesn't have 10 billion n00bies paniced about geting paid! Marketing doesn't have 1337 billion people geting banned and claiming they are not guilty...only to be found guilty by the DP jurey! Marketing is not Google. There for Marketing will never be more populer then AdSense. Google is King!
Heck, Marketing doesn't even have a sub-category, yet AdSense has a three sub-categories just to cover the first four examples!!!
Also, 1 more thing. People tell everything they know about adsense, but never tell their Marketing Secrets
Adsense is the face of money, and people thinks that by using it, they will get tons of cash. I guess they are forgetting what you said: no real traffic, no money (unless you fraud, and that will get you banned, hence more posts...)