That would be on me, I suppose, since I championed said redesign and set the reason string. In my defense, it made some sense at the time, when we required reason strings for all unstable features where a lot of them were just unstable with the only reason being everything gets introduced as unstable, and there was some hope at the time for stabilizing the trait[1]. IIRC, we've since dropped the requirement to have a reason string because most weren't actually useful, so it should probably be removed from the step trait feature gate.
That's why I had split the feature gate into two for the checked and unchecked parts, while it's been recombined now. ↩︎