>It's sure baffling how Anthropic has kept Claude Code's plan mode so linear and inflexible

It's difficult to know what the appropriate process for a model would be without widespread deployment. I can see how they have to strike a fine balance between keeping up with what the feedback shows would be best and changing the way the user interacts with the system. Often it's easy to tell what would be better once something is deployed, but if people are productively using the currently deployed system you always have to weigh the advantage of a new method against the cost of people having to adapt. It is rare to make something universally better, and making things worse for users is bad.