According to the state rules interpreter, the IHSAA is not actually opposed to the gray shirts, however, their concern is that they don't want to force everyone to purchase a new shirt. As a result, our rules interpreter was actually asked to poll all of the officals and present the findings to the IHSAA. After receiving a response from 130+ officials over the course of a 10 day period, the overwelming response (86%) was in favor of switching, while another 12% stated that they did not care one way or the other.
The NFHS made the gray shirts optional two years ago, and it's probably only a matter of time before they make them mandatory. I don't personally think that the color of the shirt has anything to do with how the officials officiate or how coaches respond to them, but I do think they look more professional. Regardless of the color of the shirts, I'm ready for wrestling!