By looking at the dates selected for YRCC games, it appears they selected dates which they are absolutely positive extra seats will be available. These dates are Sunday & weekday games which are not against high profile opponents. I assume they are hoping for a few games to potentially sell out and on those days kids tickets are not made available.
When parents have reserved seating, and YRCC tickets are in random areas, it is hard to put the whole family together when the park is packed. It's a change from the norm, but they are just looking out for issues that may arise in the case we are packing the stadium.
This is just my personal opinion. I have not spoken to anyone in the athletic department or box office.