Then it should be shown in the context of being an interesting link. I would ask also, when was the last time an ad was interesting to you? Was something in a popup, interstitial, popover, popunder, popdown, sidebar link, video preroll or post roll or inserted promo actually interesting? Was it something that you purposely clicked to find out more?
Display ads have very low click-through, yet that hasn't stopped advertisers from breaking new records in terms of $$ spent. Research shows there is a subset of internet users that click on stuff all the time- 80% of clicks are from 10% of users (that's after filtering out click fraud etc).
Beyond click-thru (which is what most web app developers will focus on), display ads/paid search serve the important function of an awareness vehicle for brands - which is what the major advertisers care about more than click-thru anyway.
