The manual steps in DNSSEC deployment mean that even if by some miracle tomorrow the root
servers offered a signed zone and began accepting requests to sign KSKs from the TLDs, it
would be years before the majority of public domains were secured, so the increase in
resources required would be gradual, rather than overnight.
The root server operators seem to have made it plain that for /them/ at least the performance
is not a problem. Several ccTLDs have deployed as islands, so they obviously don't think
performance is a problem.
There is the enumeration problem, but again that doesn't affect the root because its contents
are public. Some ccTLDs have said that they don't believe this is a problem for them either,
because local regulations mean the list of domains and registrants is public anyway. And even
for some of the domains where enumeration isn't acceptable, there are solutions to deploy
today if the will existed, and better solutions on the horizon.