Question to Jonty - do you also think marriage can be a temporary thing?
Because as a Catholic I believe that it is permanent, it is a sacrament that we solemnly vow with God to love and to honor all the days of our lives.
So marriage should not be taken lightly - we have pre-marital courses etc
Even more so for the priesthood - you have years of novitiate where you can drop out. Only when you are utterly sure for the rest of your life should you then take the priestly VOWS to God.
Service can be temporary. There is nothing wrong with having an order for lay people to give service and have institutional support while doing so,imo.