How is this any worse than trusting the original CA? There's almost assuredly some high standard they use to cross sign, and they'd get revoked if they do that incorrectly. You're failing to note that MCS was revoked as was CNNIC. So, boom, 2 bad/laughably incompetent players are out.
Trusting a CA means trusting them to write certs, even via an intermediary. If you don't actually trust them, remove those CAs.
The CA model has lots of problems, but I don't see what additional harm this actually causes.
