Raising the top marginal rate is about making a mess of the tax code, then sneaking in loopholes and shelters for cronies.
Instapundit: Soak-the-rich proposals ignore history
Exactly! How else would inane investment "opportunities" like Solyndra get traction if politicians didn't provide it?
An income tax is a terrible idea because it acts as a break on individual income. Anything taxed will result in less of that thing. Do we really want people to have less income? No! On the other hand, we don't care as much if people purchase things. So, we could correct a significant economic problem by eliminating the negative income tax, corporate tax, estate/gift tax, and payroll tax, and turning to a simple consumption/sales tax.
The problem from the political point of view is that the sales tax does not offer any obvious path to political graft and corruption, especially if the rate is fixed.