Certain types of code are cheap. Proof of concept is cheap. Adding small features that fit within the existing architecture is cheap. Otherwise, I'm not so sure. Coding agents are fantastic at minutiae, but have no taste. They'll turn a code base into a ball of mud very quickly, given the opportunity.
Preproduction code was always cheap or even free. Sales people have been selling software that didn't do what was on the tin since the dawn of time. Those features cost 0 dollars to write!
Production code. Especially production code with bugs is expensive. It can cost you customers, you can even get negative money for it in the form of law suits.
Coding agents are great for preproduction and one offs. For production I really wouldn't chance it at any scale above normal human output.
Except here's the thing, that's the sort of code that was extremely expensive before, in large part because of our day jobs (which still to this day require mindfulness and can't just be vibe-coded).
However, an extra script here or there to make your life easier, adding extra UI features based on some datapoint to your internal dashboard, ect, these were things that could've taken a few days you didn't have before to get exactly right and now they can be done with only a few minutes of attention.
While I agree with you that agentic coding still has quite a way to go and is not always producing the quality that I would want from it, I can say quite confidently that its baseline is way above some of the production code in many applications many people use today. It really isn’t that code before agents was primarily written with taste and beautiful structure in mind. Your average code base is a messy hell full of quick fixes that turned into all kinds of debt over the years.