One of their points is that RSS has a small following right now.
It's true that only a small percentage of 'influencers" use RSS. Could it be that this is the same small percentage of people who are thought leaders?
We use this in Marketing and PR all the time. We know that 10% influences the other 90%.
As innovators, opinion leaders and heavy users tend to gather together in net communities, marketers can expect such groups to exert an ever more powerful macroscopic effect on marketing. Nomura Research Institute.
Ignoring these users would not be a good idea.
Give them RSS, but keep sending email to the other 90%.