The failure of PubCenter to provide a stream of income for Windows Phone 8 developers also affects Windows Phone 8 users. With ads unable to line the pockets of developers with moola, those writing apps for the platform will have to stop depending on advertising dollars and will start charging for their apps. So instead of downloading free apps supported by a robust in-app ad network, WP8 users will have to support the entire process by reaching into their wallets and purses to pay for apps that might have been free otherwise.
One developer complained that his earnings have fallen 99.5%. Microsoft responded in one forum by saying that it is trying to build a stronger and more reliable ad serving platform. It defends the use of geographic relevance by giving the example of a U.K. eatery advertising in the U.S. That, of course, would be a total waste of an ad impression.
source: MicrosoftDeveloperNetwork via WMPoweruser