The point was somebody capable of critical thinking. Wagenknecht is most certainly in that category. And is clearly "non-rigid, non-doctrinaire", in the sense that she seems to be flying her own kite with some rather surprising opinions for someone on the "left of the left". There are examples of that throughout this diary and thread.

As for the capacity to "question oneself", I'd say there are examples everywhere, including on the hard left. However, politics is a tough show in which the actors are not allowed to show weakness, so the self-questioning doesn't get much of a public airing.