Yes, if they know for a fact that a coach is returning or will take a team reguardless of the team they roster. I also fell it is ok for a club to leave the coach spot open and note that one will be assigned if a team is formed. To me the real key is that a club be honest up front and tell the parents where they stand. With everyone trying to hold tryouts at what seems to be the same time parents need as much info as possible to make a decision that will give thier child the best chance for success.
1. If you can not tell me who the coach will be for an existing team I wonder what direction the team may be going in! If you tell me one thing and another happens well... I think you can expect the same treatment from me.
2. If you do not have enough players registered to form a team and thus have no coach assigned I will figure it out and likely take my child to another club (if this is an option) with a coach listed (again I would likely figure out ahead of time weather or not that coach/club/team fits what we need, I have done exactly this).