Alas, Flickr wouldn't even be alive if we hadn't increased the price ($$) and value (features) of Pro relative to things like intrusive ads on free accounts, etc. The very reason it's alive is because we have intrusive ads on free accounts, but no ads on Pro accounts, including for viewers. I don't expect that to change anytime soon.
We have some great plans to further increase Pro's value, but we disagree that Pro is too expensive. Relative to our peers, it's a bargain for unlimited storage, advertising free, etc etc.
Love to bounce future ideas off of you, and thanks for the article!