To me, the most important feature would be the same as the web's -- easy hypertext linking. Likelihood of human recognizing that a summarization is bad ~= ease

To me, the most important feature would be the same as the web's -- easy hypertext linking. Likelihood of human recognizing that a summarization is bad ~= ease of a human to review the raw data for something questionable. Since modern summarizing tools are operating on transcripts that are also publicly available, why not enable linking to the source material? AI summarization that littered the summary with "[0] [1] [2]" references would be the best of all possible worlds!