It is clear that Sunrail is trying to cater to the working commute and trying to keep casual diners/drinkers from using the service. The problem is, the only people I have ever heard talk about using the thing are people talking about going to the arena and to go eat/drink. I do not know anyone discussing using it for business purposes. Stay tuned, but I expect this thing to be a huge waste of money unless the schedule is revamped.
I am not familiar with this particular train, but every place I have ever lived has significantly more frequent mass transit during rush hour for the commuter than weekends and evening for the diners/drinkers. This isn't a matter of discouraging them, but because there aren't enough of them to making more frequent trips viable.
I disagree with you that they need to change the schedule. But if they don't attract commuters (the bread and butter of every mass transit system) it will be a disaster.