Yep, I believe we all agree capacity vs attendance is the problem. The Defunctland video about the history of fastpass posted earlier in this thread is so great, and really makes it clear that none of the fastpass implementations have been very good. Each works better for a particular set of guests with their goals and touring styles, but are a net negative across all guests and rides.
I don't know that locking time selections is feasible. There are probably hundreds (if not thousands) of people looking at the exact same options for Slinky Dog at 7:00am. How can you allow all of them 5 minutes to select the exact same time slot? I think of it this way: Genie+ is just an electronic/mobile version of paper fastpass. The rules are the same -- one at a time with a 2hr rule. The difference is there was a physical constraint of walking to kiosks to get your fastpass. It's not possible for half the people in the park to do that at the same time. And if you are in a line of 500 people at a kiosk you are not all getting them in the same minute. You are waiting your turn and watching the return time posted above the kiosk ticking forward as you approach the front of the line. It's the same thing but it all happens in a couple seconds. It's a worse, more frustrating experience for us at 7am, but from a cold-hearted park operations point of view, it's the same. We've traded in walking to kiosks (and carrying around paper tickets) for a more lottery type drawing of the actual time slot awarded.