a) the effective monopoly of facebook in the space,
b) of the secretive facebook-zynga deal and
c) of the sheer size of the developer community who depend on the platform financially and the investments on it
In the current size of facebook (3/4 of a billion), the excuse "but it's a free platform" is not exactly valid. Unfortunately, due to lack of a common standard (opensocial failed) and organization on the part of developers, its imposible to set a strategy. App developers have no protection against the provider.