Don't know if and how much one has to pay for the development software, what extra license costs are needed to meet the requirements of the development software, the version control software, buying the necessary hardware, taking programmer(s) from other in-house projects and/or hiring new programmer(s), re-arranging/more office space, extra HR administrative tasks, making a test environment, setting up test procedures, fulfilling all requirements to be in the Microsoft store.
I have no clue what these companies make, how stretched their employees already are etc., etc.
[bit of a rant]
Lots of headache for minimal return, if MS doesn't gain much market share quickly. And if you live in the U.S. you have a skewed view of the Microsoft corporation. They cater the U.S. market and hardly give a sh.t about the rest of the world. Here in Paraguay it is hard to get a Lumia and they are more expensive than equivalent Android phones. And these you can get easily over here. A lumia 720 for example costs here almost 500 USD.
Their attitude and lack of marketing in the not-US markets make damn sure that their WP8 phones will remain a small player. And they dare to ask why nobody wants their phones, fueling the whole chicken-egg situation. I would understand if WP8 apps require adds to make these apps profitable, however I don't know if MS wants a cut of this or not allowing it in the first place. Cannot be bothered to look it up, to be honest.
Believe it or not, even a Blackberry is a better deal than a WP8 phone over here in Paraguay. Something MS should be ashamed of.