I agree with letting the plugin creators add value in this space. The core wordpress code does not need this new feature. However, as a developer, I also see the value in how the team is being informed by the creation of a tool like this. When you write an extensible platform, like wordpress is, sometimes the complete picture of your API is not visible unless you actually build the tools that extend upon it. I’ve experienced this countless times, when I actually developed a tool for the platforms I’ve worked on. Things become clear about your core platform that you never imagined before.

Personally I don’t see any reason for this to be anything more than a plugin. I hope they don’t merge this with the wordpress core, unless it becomes so popular, down the road, that it becomes obvious to do so. I applaud the team for this effort, but I hope they don’t bloat the core with a feature that is not needed.