Yes, the purpose of the IRS is revenue collection via federal income tax for funding the government with. Said funding can then be given to the agencies and organizations I mentioned in my previous comment.
Simplified tax code means less tax money is spent on administration overhead of the IRS itself and more money that can go to programs like WIC, SNAP, TANF, and other targeted programs that are more effective aid to the economically disadvantaged.
Okay that is fair, you'd reduce administrative and enforcement costs if the tax code was simplified, but creating and managing new programs would also lead to extra overheard. I suppose to ground these arguments we'd need to discuss numbers, but its hard to generate data on this w/o specifics.
Unfortunately, Your simplification isn't really a simplification.