However, it should be very easy for the Dems to knock down this attack (but then again, nothing ever seems easy for the Dems!). For one, they can turn around and say that if Obamacare increases taxes, then Romneycare did the same in MA. Secondly, when The Heritage Foundation and Republicans designed and supported this same health-care mandate from 1993 to 2009, they actually designed and supported a tax increase. Those two points alone are enough to completely negate this word-play issue.
But ThinkProgress also reminds that whereas the ACA penalty/tax amounts to near $700 per affected household, the payroll tax extension Republicans were against late last year would've amounted to a cost of $1500 on average, or more than twice the ACA penalty figure. As per usual, Republicans are hypocritical and inconsistent, in this case arguing against a tax that costs half as much as the tax increase they were for late last year. And mind you, the payroll tax affects many more people than the ACA penalty.
Roberts knew all of this and along with his concern for how the Court would appear on the heels of GW vs. Gore and Citizens United, I believe he stepped in and uncharacteristically became a liberal, countering the dissent.
But more so, when reading the dissent, it does make clear just how radical and extreme the right-wing contingent of the Court is and can be. They have no problem with handing down rulings sans of any past precedent -- in so doing, behaving in the activist manner that conservatives have repeatedly accused of liberal Justices. In effect, the Scalia wing offer up opinions about how they wish for the country to go, as opposed to what the Constitution would dictate.
Get ready, for despite this save by Roberts, over the next 10+ years this Court is likely to reshape the country much more so than the gridlocked executive and legislative branches.