No one is arguing that the code should be secret and unavailable to certain people. The only debate is how the creation of these sorts of things should be funded. Should they be funded out of the general tax base, or should they be funded by access fees for the people that use them the most?
The latter doesn't seem like a horrible model to me. It's not unlike how road construction is largely funded by a gas tax.
Government likes model laws and codes because it's easy and they can just reference them -- that doesn't mean that the law should be limited in availability. The trade associations can still require payment for services, just like Red Hat can sell subscriptions to Linux.
Public access to law is about more than building codes. In many cases, government has sold the rights to the law to companies like Thompson. I worked for a government agency that actually had to pay for a subscription to both the law and regulations that the agency actually produced.
The latter doesn't seem like a horrible model to me. It's not unlike how road construction is largely funded by a gas tax.