Because Jack is on vacation, I thought I would offer some help on this question. Of course, jack can add his own reply when he signs on next.
Once the lower seating area fills up and there are no more availlable spots for anyone to sit, they close off the entry points to the lower area by placing a rope across the entry point (along with a CM to answer questions and let guests in the seating come and go) as there is no point in any additional guests going down there because it is full.
Having worked in Special Event Planning for 10 years, I just don't see risers making sense in this location. Once you see the set up, you will see that it would be quite involved to add risers. First, the chairs get set up and taken down EVERY day. If you have to add risers to that, you are adding to the labor intensity of the set-up process. Also, from a safety perspective, for them to set up risers that are large enough for guests to sit on them, would be quite involved.
For those who want a chair, or want to sit in a reserved area, or do not want to camp out for a seat (which is NOT necessary although some do chose to do so), the reserved area is perfect. The treats, the beverages, and let's face it, the VIP treatment that some people love are all value-added elements that can be received for $59. Is it worth it? As with everything, only each individual person knows the answer to that question.