> I "code" using Codex but I still use PHPStorm for checking diffs, database access, reviewing PRs, and the debugger. The value proposition has changed, not disappeared.

You are able to do this while the output is small enough. But, it will not stay small for long. Business expectations are rising fast. To stay competitive, you have to push large amounts of code/fixes/features. There is no way to manually review it or QA it. If your org is not there yet, it will eventually get there. Or it will die out. It is only a matter of time.