I'd say better this that having "cipher agility" like with IPSec. During design of IPSec, someone was advocating for the "NULL cipher" which is essentially no-

I'd say better this that having "cipher agility" like with IPSec. During design of IPSec, someone was advocating for the "NULL cipher" which is essentially no-encription where the use case was "debugging". Tie in cipher agility with the NULL cypher, and you've got yourself an awesome downgrade attack