A very succinct reason for worrying about deflation.
The problem is that deflation — falling wages and prices — is always and everywhere a deeply painful process. It invariably involves a prolonged slump with high unemployment. And it also aggravates debt problems, both public and private, because incomes fall while the debt burden doesn’t.
When Rand Paul and Pete Peterson talk about cutting the deficit now during a period of high unemployment which can get much worse if government isn't helping keeping some spending going, this is what they are advocating. Bad times for almost everyone else so the wealthy can hold on to their wealth.