WASHINGTON — For a law whose admirable goal is to ensure better health care at lower cost for all Americans, the Affordable Care Act has come under remarkably varied and persistent attack. The latest volley concerns the obscure issue of how to apply a penalty on individuals and businesses that fail to obtain health insurance, and who thereby put all the rest of us on the hook for big medical bills. This penalty, which is intended to encourage the classic conservative value of personal responsibility, will be collected as part of annual tax filings, a reasonable and efficient method that’s only objectionable to those whose real objection is to the whole concept of health care reform.