Why is the recovery so mild?

Because of the uncertainty that goes along with it:

In terms of discouraging a rapid recovery, other government proposals created greater uncertainty and risk for businesses and investors. These include plans to increase greatly marginal tax rates for higher incomes. In addition, discussions at the Copenhagen conference and by the president to impose high taxes on carbon dioxide emissions must surely discourage investments in refineries, power plants, factories and other businesses that are big emitters of greenhouse gases.

Congressional "reforms" of the American health delivery system have gone through dozens of versions. The separate bills passed by the House and Senate worry small businesses, in particular. They fear their labor costs will increase because of mandates to spend much more on health insurance for their employees. The resulting reluctance of small businesses to invest, expand and hire harms households as well, because it slows the creation of new jobs and the growth of labor incomes.