Parsing Roberts's Obama Care Ruling

After days of fuming over Justice Roberts's egregious Obama Care decision, I shocked myself this morning by finding grounds on which to support his ruling. I still abhor Obama Care; I merely note that I can make some logical (but probably not legal, given my lack of legal expertise) support for the awful decision. I will have to begin by assuming that it is reasonable and correct for Roberts to redefine the penalty as a tax. Such procedural questions are outside my bailiwick. The reduced question I wish to consider is:
Is it a significant expansion of federal power to say that the government has the right to coerce participation in commerce by means of the tax code?
  To remove partisan considerations from this question, recall that most Republican plans for correcting the distortions in the health care market include giving individuals an income tax deduction for purchasing health insurance. Therefore, the GOP plan (which I have heretofore supported) includes a measure which reduces taxes (a penalty by another name, according to Roberts) for those who purchase health insurance. This is logically equivalent (plus or minus a tax increase) to penalizing those who do not purchase health care. Of course, the Democratic plan implies an implicit tax increase, whereas the GOP plan does not. So, in the large, the two approaches differ on the mandate issue only on the issue of tax rates. No one argues that Congress does not have the right to raise our taxes. Hence, if we grant Roberts's redefinition of the penalty as a tax,  the two parties seem to agree that the mandate is constitutional.

Of course Obama Care is not the first instance of the federal government requiring, through taxes/penalties participation in commerce. Every year when I pay my income taxes, I pay the penalty for not participating in the home mortgage market. My taxes are higher than those of my colleagues with large mortgages. Nonetheless, despite these penalties, I have refused to buckle to federal coercion to support the banks by selling them a mortgage on my home.

  As I chew on this thought, I still come to a different conclusion than Roberts. Roberts's argument is essentially that Obama Care is the reductio ad absurdum of our current taxing policies. That mortgage deductions pave the way for Obama Care do not justify the latter in my mind. Instead, it suggests that such tax policies contain hidden erosions of our freedoms and should be disposed of with Obama Care.