> "I think the most important mind shift is from "let's make this extendable by plugins/scriptable so we can modify it while it's live" to "if requirements change, let's just change the source code and redeploy"."
People who develop web apps can go ahead and have this epiphany, but this obviously doesn't work where you don't have complete control over "redeploy", which is a large class of software.
Sure, deployment can be tricky, however the big question then is if you make it extendable by plugins or scriptable then is the process you will use for testing, managing and deploying these plugins or scripts any easier?
I have seen cases where you go to pretty much the same effort as the "core" deployment, so the deployment benefits of the configurable option were fake but the complexity costs were real.
People who develop web apps can go ahead and have this epiphany, but this obviously doesn't work where you don't have complete control over "redeploy", which is a large class of software.