For some reason people here seem to forget that customer experience is no longer the driver for decisions. It's maximizing revenue and squeezing every dollar from every guest they possibly can.
Why do people think Disney will limit the number of LL reservations so the standby line remains somewhat reasonable? This is one of the reasons for 7am reservations. That way from the very start of the day standby lines will be greatly inflated. As guests begin using Genie to check wait times and suggestions for what to ride they will see inflated wait times. A box will pop up stating that the current wait time of (insert ridiculous line length for 10am) for Jungle Cruise is the shortest projected time for the day and suggest you ride it now. Why wouldn't they then tack on, "Or, purchase Genie+ and book a LL for it for 11am".
While not likely to happen at rollout or until full crowds return, what this new system is designed to do is make LL the main line of use. Standby lines will become like the standby airline ticket. Everyone else is buying the more expensive "guaranteed to ride" ticket. IF....IF we still have room for you we will let you on.
Since you can only book a ride once a day with Genie+ it's likely the LL lines will reduce in volume later in the day. However, that means those guests will be using the standby lines to reride later. Those who think they can wait out the LL lines to shorten will then experience increased bodies in standby.
I personally feel that Disney will do whatever it takes to squeeze and pressure as many non-Genie+ purchasers into caving and buying after they already are at the park. Additionally, after experiencing long waits they may hope it will drive people to buy Genie+ for the remainder of their park days.