The argument I've heard is that so righteous indignation over the "staggeringly high" taxes "stolen from the hardworking American people" or whatever. This is one of the same arguments as to why sales taxes shouldn't be included in the shelf price of an item or service.
Except it doesn't work. People can be mad about taxes regardless of whether they're easy or hard to file. (Paying taxes is straightforward; the vast majority of us have it done for us from our paychecks every interval.) And where I live, public votes to raise the sales tax for various projects, often public transit, rarely if ever fail.
It seems to me just to be an excuse to not actually deal with our busted as hell tax collection system because that system benefits people who themselves have an excuse to rile people up about taxes.