Actually, I'd suggest that licensing of lawyers violates the constitutional guarantee of a right to an attorney. It is viewed by the modern system as a positive right, an obligation on the part of existing attorneys to work for you for free. But that is obviously not what was intended; it is meant as the right of anyone to be represented by a designee, as opposed to being required to represent themselves, and this has been criminalized today.

i do believe there is a certain responsibility a lawyer swears to ethically uphold and maintain toward lay society which justifiably warrants some reasonable evaluation of the degree to which the candidate is able to comprehend and/or adhere to that oath.

This is just an argument that licensure has benefits. That's true, but they don't exceed the costs.