Ironically because it might be the conservative thing to do. This commentator points out that Chief Justice Roberts tends to yield to history and precedence when deciding cases and there is little precedence for making a decision which drastically changes the court's interpretation of the commerce clause and throws out what has been accomplished with expanded Congressional power under the commerce clause.
A historically minded judge -- such as Roberts -- will be well served to
recall the difficulties that Federal courts encountered during the 60
years preceding Wickard in distinguishing between Federal
statutes that legitimately affected "commerce between the several
states" and those that allegedly did not -- cases involving things such
as antitrust laws, the Pure Food and Drug Act, restrictions on child
labor and alcohol distribution and the creation of the NLRB. That is
another reason for why the Roberts Court will, in my opinion, decide
that legal challenges to the individual mandate are too much of a
departure from legal precedent and too fast of an assault on the citadel
of Federal powers. Such a decision would be profoundly conservative --
in the best sense of the word.
