The more I watch the unfolding fiasco of the ACA the more I notice that it's not affordable, and it doesn't help anyone's health. What it seems to be about is establishing precedent for the president to rule by decree.
Think about it. The president changes dates, requirements, mandates, whatever by simply announcing the change. This is the sort of thing that used to require a bill amending the existing law to be passed with appropriate debate, by both houses of the Congress, then signed by the president.
Having established precedent, declaring the congress to be superfluous should be easy.