I don't think you've really considered the practical effects of "unless someone has put in place measures to do identity and authentication of all people that enter, they don't have the rights to keep out unwanted parties."
Evading a MAC filter should be equivalent to criminal trespass (usually a misdemeanor). There isn't any such notion in the law.
So the problem I have is with the structure and application of the CFAA, not so much with people having the right to keep out unwanted parties.
I did not put it clearly above, but I specifically meant unauthorized access where the CFAA would apply (in my world view, for circumvention to be a felony, the network operator needs to have some expectation the security mechanism will effectively prevent access).
If all we were talking about was just getting onto their network, then I'd agree. Just walking into a store where I'm not allowed should be a misdemeanor. Charges could increase, possibly to the felony level, depending on what I do after I'm in the store.
If MIT were tracking down someone who kept on using the network to send out shitloads of spam, and that person kept on bypassing all of MIT's countermeasures, and that person dropped a physical box into a wiring closet at MIT, no one would be confused about this.
in my world view
I disagree with your world view, but for now we can leave it at us disagreeing.
