The main issue (fallacy?) here is to assume that if Nokia comes out with their own platform/OS/services then they'll be guaranteed success... And that it doesn't come with additional RISKS AND COSTS that are considerably higher than if you're renting them out from the likes of Google.

Of course with the greater risks and cost, there's a potential of higher reward and we've also seen that Nokia have made some of the investments (OS developments, alliance with intel).

But the downside is that Nokia has some terrible track record when it comes to launching their own software & services: ovi store, ovi mail, maemo apps, ngage, etc.