Their sensational, media-grabbing reports on medical errors are eroding trust in the medical profession, which is not always good:

The now famous IOM report on medical errors – To Err is Human had as a goal to improve medical care. The authors, honorable though they are, contributed to decreasing trust in our medical institutions. Many have debated the validity of this report, but few would debate the negative impact this report has on perceptions . . .

. . . Even if the report is 100% accurate (and many critics suggest hyperbole reigns in their estimates), the authors did not consider all the potential impacts of such a report. Or perhaps they did and did not care about the negative impacts.