Here's the thing though. Online, the biggest issue (for publishers) is that you CAN measure ROI.
If you book press, radio, influencers then the best you get is a good feeling that the money kept your brand front of mind and drove some untrackable sales.
Online, you get advertisers complaining that they spent $x with you and only tracked $y of sales, and all considerations about brand building, 'front of mind', sales driven through other channels as a result of the ad etc disappear.
I turned down an ad booking for Head for Points yesterday because I knew, given what was on offer, it would never cover its cost in direct sales and I couldn't be bothered with a lengthy autopsy afterwards. I will stick with AdSense in this case and get a fair % of the money with zero hassle and zero payment delays.