Fair enough :) when looking at the big picture, you're absolutely right. Factoring in all levels of taxation, there's a lot more balance going on in terms of total tax owed.
The problem is, it's a matter of state-level taxation, and on a state level (in Washington), the taxation is regressive. In the past three years, I've made between $20,000 and $24,000/year, and I've never qualified for any state-level subsidies or breaks. So, as a working person in that bracket, in Washington, I pay a good five times as much of my personal income in taxes than my wealthier co-citizens.
Now, I don't personally feel like I'm being overtaxed. However, for a state to lean most heavily on it's poorest citizens for funding is just ridiculous. At the very least, it should be an even, proportionate contribution, and that's what this income tax intends to do. Plus, an income tax is just more sensible, as it only taxes the people who are actively making money in the first place.