This is a very complicated topic. It would make a great topic for a forensics event. My take:
1) All or none statements are a little over the top.
2) A national, unified exam is the way to go. However, the problem is state laws are very difficult to change and certification (or lack of) is on a state by state basis. I believe CPAs have a unified exam and this has served accountants very well.
3) We are a long way from requiring a 4 year degree to be an optician.
4) There are many types of opticians. Some are really sales people working on a commission. Others are technicians in a lab. Not sure if this is an issue or not, just pointing out that an exam needs to be inclusive of all of the skills required of an optician and will be more difficult for those who "specialize" in one area of the practice.
5) Other professions have advertised the value they provide to the public. The American Institute of Architects comes to mind. A "look for an ABO" certification could have some impact, but the lack of a well funded national organization hurts this effort.
6) The general mood of the nation is to have less regulation. Opticians, with all due respect, do not command the respect of architects, engineers, pharmacists, accountants, lawyers, MDs, etc. that all require professional registration to practice. I am not saying this is right, I am just saying this is the general perception. While other professions that do not require a college degree such as hair stylists and manicurists need to pass a test in many states, there are many, many other professions that do not require certification.
7) Many of the pro-certifcation people have "protectionist" tone to their argument. Keep things the way they are or adapt rules that will put things back to the way they used to be. I am not sure this ever works. You will not stop the chain stores, the imports, the websites, etc. We are in a world that is accelerating in terms of change. Focus on adapting to the change and capitalizing on new opportunities rather than fighting change.