If agents really are superpowerful at programming tasks why not just have it rewrite the tool that the majority of your customers use and have it recreate the bugs? I mean presumably its the primary force behind the current version so what's the major cost there?
I imagine it comes down to economics.. there isn't much upside to fixing the last 20% of issues that the dumber faster models are missing.
The cost to serve, latency profile ,and internal demand for a maximal intelligence model would probably keep it pointed at harder and more valuable problems most of the time.