Insurance is the main reason ground runs are being done less by engineers. That being said, insurance companies are responding to things that have gone wrong during run ups. I have seen an engineer cook a turbine on a start, pound out the striker plates on an MD369 by starting with the cyclic off centered (hell of a racket), and I myself did a 180 degree spin running an AS350 on an icy pad (scared the s**t out of myself). Things can and do go sideways during a run. Granted training was an issue in all the fore mentioned incidents, however, the simple fact is, as engineers we just don't do it often enough. As a younger engineer I thought it was better not to bother the pilot for the run but now I am happy to bow to their experience. I would rather have someone at the controls who can respond in an emergency.