An analysis from ArsTechnica
Microsoft's $100-per-app bounty is both too much and not enough
In an argument put forward by former Microsoft employee Charlie Kindel (who led the company's developer outreach efforts for Windows Phone 7), it does more than reflect a wilting app market. This move attracts developers who aren't particularly invested in the success of the platform (and hence in the quality and support of their applications), but are trying to make a fast buck from cranking out simple applications.
However, such payments can be useful for priming the pump of a new app ecosystem. Microsoft has arguably had some success thus far in bulking up Windows Phone's app marketplace through offering incentives to developers. And BlackBerry has offered $10,000 bounties for apps developed for BlackBerry 10 (though this is not a blanket offer; apps must generate $1,000 of revenue in order to qualify).
Microsoft's $100-per-app bounty is both too much and not enough