I'm not a fan of the additional red tape and fee's associated with the COA. I imagine it can get pretty onerous if you want to work in multiple states/provinces.
One or two points I have seen tho in favor of the COA...my experience is with the FL rules.
First, it forces corporations to secure a more long-term relationship with an engineer. Believe it or not there are many engineering companies out there that are not owned/operated by engineers or who regularly hire/fire lowly project engineer's or who hire one or two engineers and have no continuity of policy or understanding of engineering concerns. The COA rules put an engineer into upper management since the actual named position of the engineer qualifying the company must be named in the bylaws of the company.
Second, there will be a permanent engineering position over the professional engineering policies/standards/procedures of the company. Again try to imagine a large company with nothing but project engineer's or a large manufacturing or steel fabricating company who hires only ONE engineer...these engineer's have no or little say over company marketing, client selection, client commitments, contract development, PLI selection, engineering standards, etc. They have no peer group or mentors in the company and the good intentions of a green engineer in such a company can be easily swept aside.
If a company wants a new lowly project engineer to qualify their entire company then there should be resources, a title, a pay raise, and authority, to say nothing of an understanding of professional concerns, that goes with the burden of responsibility and accountability.