Democrats use taxes for social engineering and to curry favor by telling the poor that they are helping them and they are making the rich pay for it.
Higher taxes gives the government more control, but not necessarily more revenue, and when the economy is growing slowly, they can definitely result in lower tax revenue.
However, a bad economy while Bush is in office is good for the democrats, and they want to be able to blame the Republicans for a bad economy in order to win the White House in '08. After all they still take credit for the great economy the Clinton inherited and turned into a recession by the time he left office.
"and they want to be able to blame the Republicans for a bad economy"
They even blame Republicans for a bad economy when there is a great economy.....