The IRS already prepares your taxes for you. There is simply no way around this: they have to prepare them to check the numbers they get from personal filings (or from Intuit etc). The additional service is the one that compares the forms people send against the form the IRS already has, and then has to follow up on every minor discrepancy.
So the direct-to-I.R.S. proposal isn't adding anything new to big government: it's eliminating an utterly pointless literal box ticking service they currently provide for free, at the expense of tax payers, and for the benefit of Intuit and pals.
If you think filing taxes is annoying, imagine working at the IRS with this system.