The undergarment is what a mormon wears after the 2 temple ceremonies that are to give them extra power and protection. It is kinda like a clerics robes, but not shouting to everyone at every time. The first designs had turtle necks and long sleeves. The "important" part of them are the symbolic parts which are not at the sleeves, so generally this is part of the general movement of mormon church policy away from "we made these policy rules black and white so it is easier for you to measure personal commitment". The church recently likes to go by "the restored church of Jesus christ" as a nickname instead of mormon. Additionally, with the opening of "Grey areas", the lines between doctrine, temporary policy, and sometimes cult like culture are easier to see. According to the People I talk to, this is a non issue.