OK. This reason is kind of boring.
The Health Care Bill was passed through a Senate process called "reconciliation". This is a process reserved for budget fixes that was invented in the 70's. What's unique about the process is that it allows the Senate to pass bills with 51 votes instead of 60 votes. This was invented so government wouldn't get all tied up with endless debate over something that was supposed to keep us in the black or change tax stuff around.
Reconciliation was never intended for the broad, sweeping legislation found in the Health Care Bill. In fact, not even close. It's never been used for a bill even close to as big as this. The majority party stretched a "special case"-type exception to the rules in order to push one of the cornerstone policies of the President.
Along with this, there is a special rule about reconciliation. It cannot cause the government to go into deficit (to lose money) for more than ten years. It appears this was overcome with fuzzy math. These type of programs always cost more than the paid experts say. Saying this bill won't be costing us for more than a decade would be like saying Medicare, Medicaid and Social Security are big money makers.
In short, the majority party appears to have done all they could to avoid a vote by the people the public elected to represent them. If the Senate would have used the correct procedure--which they should be expected to do--they would not have had the 60 votes required to pass the bill. Using the incorrect process, it was passed.
It doesn't matter the bill and it doesn't matter the political party. I am against this type of behavior in government.