This is adequately covered in draft-ietf-snmpv3-rfc2570bis-03.txt. Rather than burden MIB documents with references to protocols we no longer recommend, a informative reference to rfc2570bis (whatever it is whenever it is) is sufficient.
I agree that it would be good to significantly reduce the amount of boilerplate that goes in every MIB. Pointing to a single reference would be much more reasonable. Margaret