not sure what the margins are now, but for iPhone 1.0 total end-end cost of the phone was something like $284 for the $600 phone. whatever the fuzzy math here, with Apple on projection to sell 10million + phones this year, they are making an absolute killing.
and thus, to the bottom line in the short term, it's not necessary at all to appease the developers -- they quality of some apps is very very high already, and will continue to do so while both independent devs and companies are also making a killing for arguably little work (a few months) and huge roi.
the long-term is that controlling the end-end solution with an iron fist will be just one of the many restraining factors that keeps them from gaining market dominance (single carrier, no keyboard, one phone model, et. al).
too bad so sad -- their way or the high way.