I agree. Plan mode came about because earlier models were loose cannons, doing what they pleased. Today's models follow instructions better enough to not need a separate mode. However, there is still value in using a separate, smarter model for planning than execution, and persisting it for auditing on completion.

If you do use plan mode you might like https://plannotator.ai/

I typically converse with the default model to point the plan in the right direction, then have it iterate with a smarter reviewer to find flaws until the plan file is converged.