It's rather disingenious to say that an SSL cert is $200, when in reality a domain-verified cert goes for about $20. Hardly anyone interested in Namecoin would be needing EV certs.
I mean... your cost argument is weak, almost meaningless. Just focus on the trust angle, it's a reason enough against PKI/SSL.
IIRC they used to have a ridiculously awful method for revoking a cert. Is that still the case?