Advertising in RSS is just starting now, for all practical purposes. If we wanted to, as an industry, reject the idea, we could.

When XSL stylesheet integrationbecomes astandard featureacrossa majority ofRSS readersthe issue becomes moot. There is no need for industry widerejectionas this will ultimately come down to choice: "To Filter" or "Not To Filter".
Adsense basedRSS Advertising as currentlyimplemented (bearing in mind the fundamental intent to perpetuate obtrusive advertising in a popular new realm) is hillarious when you really come to think about it.
XML and Obtrusiveness are mutually exclusive. This attempt to inject advertising into RSS may go down as one of the greatest pieces of XML tutorial material of all time. It could also serve as yet another example of how Web 2.0 is fundamentally different from Web 1.0.
Will we ever truly comprehend the unadulterated meaning of: "Free Will" ?