Why do people assume families would prefer earlier FO times. Maybe for the walk up / newbies but for ST holders no. Committing to a full season is expensive, my 10 year old has dance, urdd, sports activities and birthday parties for her friends on the weekend most of which will end approx 4 - 4.30 at the latest. Let alone doing something (sunday dinner with grandparents, afternoon shows and god forbid just going out for a walk).
4pm FO take the entire day out once you take into account sunday dinner. 6pm FO also allow you you to have tea before the game. 4pm means families are going to have to face the kids needing food (everytime) in the rink adding to the cost of the game.
Think about the volunteers who come down a minimum of 2 hours before FO. That would mean 2pm latest arrival.