If you believe GDP growth will remain tepid and the another recession is on the horizon...why would you raise taxes on the middle class?
Every dollar of an upper class family's income passes through the middle class tax brackets. So, by 'protecting' the person/family that is barely in the middle class bracket (and would only see a small portion of their income hit by higher taxes), you are missing out on trillions of dollars in revenues (over a 10 year period) from other family units that can afford it.
There are more (and larger) tax breaks for the middle class than ever before. IRA tax break (up to 5000), Saver's Tax Credit, EITC, Child Tax Credit, American Opportunity Credit (college tuition write-off), Lifetime Learning Credit, Student Loan Interest credit, Child care tax credits. Plus all the other tax breaks that small businesses get that are not afforded others.
Granted, if you are a high school educated, twenty-something, single and making a middle class salary .. you will not see most of these breaks. But they are out there and people are using them.
Unless you believe deficit reduction is an important moral goal for its own sake, then the whole point of closing the gap is the benefits to the country in economic growth and stability. Because we're still in an economy with a lot of slack and at the zero lower bound for monetary policy, sharply reducing the deficit this year would probably be counterproductive for those goals.
Maybe you are right, but we seem to be heading in unchartered waters here (long-term). SO, while it would be foolish to expect (or even want) a balanced budget, it's not foolish to want more done than is currently proposed. This country just went through 4+ years of trillion dollar deficits .. more than 20-30 percent in revenues/cuts is not a big ask.