The silver lining is that the parents don't HAVE to do this. If people want to pay market price to provide a benefit to their children, with no subsidy, that's not a major issue. Having the government force the issue would be a bad thing.
This isn’t necessarily true in CO. A child can force parents to be kept on a policy, just like parents can be forced to pay for education if the adult child is in college.
It also means an insurance company has to keep an adult on a policy which can raise the premiums for the rest of the group to cover the true underwriting costs.