I think Nokia understands that Apple gets 30% of the $200mil US/mo revenue, generated by "3rd party vendors" in the app store (per recent CNBC report "Planet of the apps"). The cost:benefit ratio of trying to develop "in house" is most likely not feasible. Don't forget, if they develop apps, they would need additional resources to support them.

I'm really waiting for the ability to connect to my sling box, but that's not Nokia's responsibility.