They're expensive to perform and rarely are reproducible but I'll wait for the empirical studies before believing any claims.

We can't even decide if type systems have made us more productive. It's barely been studied. Same with test-driven development.

What it sounds like we'll see, from your description of AI-enabled developers, is a commensurate (perhaps linear) increase in the rate of errors reaching production systems. Every line of code is a liability. Now everyone has a fire-hose they can aim at a production environment.

At least time and effort prevented some bad ideas and potentially bad code from reaching production.

I'm sure the platforms providing these tools are going to be happy with the results when every business writing code this way becomes dependent on them and have no exit strategy. The prices increase, the service gets worse, and you're locked in. Sounds real productive.