It's generating a huge portion of our tax revenues,

The subsidies encourage people to get insurance at work, stifling the individual non-group market, and they encourage employers to provide overly generous insurance since the cost is subsidized. What's more, the subsidy is upside down - aiding mostly the high-income families that would probably purchase insurance under any scenario, and providing little aid to those of modest means.

The deficit is a little smaller because of this voluntary tax.

There was a proposal in Congress that would raise a point of order against any tax proposal that would not deal with the AMT. It died.

[That's not to say there haven't been efforts to reform the system.] There was a proposal in Congress that would raise a point of order against any tax proposal that would not deal with the AMT, ... It died.

[Still, such a idea is political dynamite.] The politics are impossible, ... Politicians do this at their peril.