The conspiracy theories are ludicrous. Failure of the Hillary initiative floundered on the delusions of the WH that they could outsmart and steamroll everyone else with their 'manhattan project' plan, playing around the major political obstacles (i.e., insurance companies), appeasing others, etc. Their model is always take existing public support as a given and work very conservatively within perceived constraints. The idea of taking an idea that isn't wildly popular and selling it -- spending some of their 'political capital' -- is foreign to them, except when they perceive it as economically 'essential' (such as NAFTA, or tax increases/spending cuts for deficit reduct).
Going for STark or some other plan after they committed to their own (and alienated their own allies on the Hill) might have worked, but could easily have failed. It would have been an admission that their own work was a hash. Could be some sin of pride involved here.
For those fond of a simple marxoid explanation, the problem is that assorted economic interests could benefit from some kind of health care reform, including many of the U.S.'s most substantial corporations. At the same time, many workers would not much benefit from a reform. They already have good coverage. There is not necessarily a neat class divide on this. Broadly I would say there is, but it is not necessarily overwhelming.
If there was some burning capitalist interest in privatized health care, we would observe more attacks in European nations. Instead, from what I can see, the pressure is on retirement insurance, not health.
mbs