It's pretty obvious politicians can not or perhaps refuse to serve the wishes of their costituents.  When I pay taxes I want to put my money towards the things I believe in.  Instead of just paying a dollar amount and hoping they apportion the money in a good way, I want to decide specifically how much money goes to what government projects.  Of course there would have to be minimums for defense spending etc., but the ability to appropriate money where we want it to go seems much more democratic than the current tax system.