There must be a way to finance a government at the very least for maintaining peaceful relations, conducting a military, providing for a national security, and a court system. We got along fine without taxes before the 17th amendment and we'll get along fine after it. However, we still need a way to fund a government.
So why not have spending cuts? My actual belief is that taxes are a necessary evil, but they should be as low as physically possible for individuals, and levy slightly higher taxes on businesses. Still a flat tax across the board, though. I believe that, along with this, there must be spending cuts. In every department. Healthcare, education, welfare, infrastructure AND defense. You can't say you support spending cuts except defense, because that's like saying "yeah I hate people who smoke cigarettes, but I'm gonna go chew some tobacco now." It's the same thing, but with a different name. Higher defense spending leads to bigger Government, which is why I'm so apprehensive about Government in the first place--it's inherently destined to become bigger and crave more power, which ultimately leads to oppression.