Punishes people for being wealthy. Ironically the demographic hurt most by this is the middle class. They're in the no-man's land between not paying much income tax, and being able to utilize the tax code to it's fullest.
Why punish people? Institute a flax tax rate.
No, because one it is unsustainable. Two because of the way numbers work a flat tax is not fair, it puts more burden on the poor and the middle class and less burden on the wealthy.
Quick example....
Lets say you have a 10% flat tax rate.
The Rich Man makes $1,000,000 a year. The Middle Class Man makes $100,000 a year. The Poor Man makes $10,000 per year.
after taxes
Rich Man - $900,000, Middle Class Man $90,000 and Poor Man $9,000.
Now the Rich Man that $100K loss looks like a lot of money, but it is not going to really effect his life style. The Middle Class Man, well he is taking home around a grand less per month, so he is going to have to make changes. The Poor Man, he taking home $750 a month after the tax, without it would be $830. For him that extra $80 is huge.