Big milestones require a proper ceremony. Getting promoted from Brownies to Girl Scouts had a wonderful bridging ceremony that made you feel really special. Marriage has a whole bunch of special elements which are designed to help you move into a new phase of life. Retirement brings the obligatory gold watch to signify something (maybe that you will have too much time on your hands?) not sure about that one. Anyway, ceremony is a big part of recognizing life-changing passages.