Texts produced by NLG systems need to communicate valuable, useful, and accurate information. I would love to see more research on content production and selection in NLG.
NLG texts need to communicate good content as well as be accurate. Rule-based NLG systems are very good at accuracy, but sometimes struggle to reliably choose appropriate content in a wide variety of circumstances.
Some thoughts on the properties texts need to have in order to be good non-fictional narratives, and speculations on how we might generate such texts.