A nationwide identity card program in the United States would be less convenient than the status quo because it creates an intrusive system that allows Uncle Sam to check on its citizens. It should be up to the states to issue ID cards because of the 10th Amendment's separation of powers clause. It would take an amendment to the U.S. Constitution in order to get a national ID card system going, so even getting the system off the ground is inconvenient even before it starts.
No, identity cards would not be more convenient than the status quo, because anything produced federally is slow and laborious. Things produced on a state level are made faster and have fewer instances of fraud. It would be expensive to have national identification cards, and state cards seem to work sufficiently. There is little to be gained at much cost by having national identification cards.