> Congress has delegated the authority to make these decisions to regulatory agencies
Yes, but at some point there must be a limit to how much power they can delegate. If Congress created a new Super-Congress that it granted all the powers of Congress, I would contend that would be unconstitutional. It clearly goes against the founding principles of having three branches of government. That would be akin to the government creating a fourth branch without amending the constitution.
Amending the constitution is a process that is clearly defined by the constitution. If that process isn't needed to create a fourth branch of government, a change that changes the core of the constitution, what would it ever be needed for and why would they have included it?