As a con attendee, I generally like to have programming to attend in the noon-3PM Sunday range. I feel a little cheated by a con where I have nothing to do Sunday but check out and drive home, no matter how good Friday and Saturday were.

Also, cons that are worth attending generally already have way too much crammed into Saturday, even when half of the con's scheduled programming is Friday evening and Sunday. Even if there were function space to hold the Sunday events on Saturday, it would just add more "I have three events I want to get to at 2:00" frustration.