I think the main issue is the expense of developing and supporting F1 teams, which doesnt seem to mesh with the current financial problems that the car makers are experiencing due to the global economic downturn. Especially when the overall performance of the teams is not what one would call spectacular. At the same time these car companies are working on becoming greener, and F1, as for any type of racing league tend to consume lots of fuel; in effect being hipocritical.
Unfortunately the technological advances that have come from F1, and found their way into production models will suffer from the pull outs.After all racing tends to make for good automotive research.
Scream till you like it.