A friend's friend gave him the following analysis which he then passed on to me, and I found it rather interesting. All I can say about its author is he's a conservative with a background in law and tax accounting.
"Justice Roberts is brilliant. I believe his siding with the liberals in the Obamacare decision was for the following reasons:
1. Calling the penalty a tax is reasonable since money extracted from a citizen under duress and absent a quid pro quo is a tax. This decision enables two shots at overturning Obamacare as enumerated next.
2. Sustaining Obamacare removes a victim issue for the Dems to campaign on this year and gives the GOP an opportunity to present a positive view of healthcare changes. Done right, a new president and Congress will make the changes.
3. Failing success in number 2, the payment of the tax in 2014 will enable persons to challenge the tax on the grounds that the taxing authority of Congress, now thought to be limited, is indeed limited if used to compel behavior otherwise prohibited by the Constitution. That is, if Congress cannot use the commerce clause to compel behavior, it cannot use another power granted in the Constitution to negate the specifically prohibited power of another section of the Constitution. Thus, that is why SCOTUS specifically ruled that Congress cannot use the commerce clause to compel the purchase of health insurance.
Leaving Obamcare in place also allows the HHS mandate for all employers to provide birth control, etc. to continue to be challenged under the First Amendment by the Bishops, Notre Dame, etc."