I still use plan mode. I use it for large features that I haven't fully thought out. Which I guess is like the author's "planning" phase. But I don't see the issue with using plan mode for planning. I welcome the agent to ask me for questions and clarifications. Do I read the full spec it produces at the end? Usually not. Usually the agent is smart enough to highlight the important tidbits and assumptions. I read those.

It's particularly important when you're making architecture changes or things other features will need to build on top of. I want to know what libs its going to use. The nitty gritty details I don't really care about.