The wildcard in LLs has always been the DAS...Disney could (and did) cap the number of Genie+ and ILLs being sold so that the line kept moving, but with DAS being handed out like candy, often for more than the 6 that Disney said they would limit it to, there was really no way to effectively manage LL capacity.
I'm probably in the minority, but I don't see this as a money grab by Disney, and I don't think they're looking to sell more Genie+ - I think they finally recognized that a) people who buy Genie+ are unhappy about the long LLs, b) DAS became ineffective for many who needed it because of the long LLs, and c) standby guests were increasingly upset about the LLs were making the standby lines unbearable.
I'm sort of in your minority... still a money grab, but for different reasons than what normally gets pushed here. I think the uncertainty of the true time spent in a queue, especially standby, is translating into lost vacation bookings. They aren't trying to sell more $30 Genie+, so much as they are trying to avoid losing out on $5K bookings.
Like someone else said, we don't even try to ride most attractions with ILLs and several Genie+ attractions like Frozen, Ratatouille, Slinky Dog, because the standby lines are too painful. It's not even the posted wait, it's the posted wait plus the uncertainty. I've mentioned before getting in lines that were posted as 70 minutes that in actuality were 150 minutes. Lines that we waited 45 minutes in and the ride went down, queue cleared. Get up to rope drop DHS and RoTR, SD, MRRR AND ToT were all down at park opening.
For us, we didn't pay to get in the park, so we roll our eyes a lot, and it makes the day disappointing, but we aren't out money like the people around us are. How many times do you have a day like that, avoiding headliners, getting stuck in lines longer than posted, before you say, "Why even come to Disney?"
I think the shell game finally caught up with Disney. They had significantly more people entering the gate, than could theoretically ride all the E-ticket rides they wanted. In ye olden days of the Magic Kingdom, when there were 9 E-tickets, if you missed one or 2, you could still have a successful day. But the way Disney operates and advertises parks now, if you miss the Pandora attractions, or RoTR and Slinky Dog, how would you rate your day at AK or DHS? Actually, that could be another thing... there has always been an imbalance between MK attendance and elsewhere, maybe it's gotten worse. "Go to MK, you'll at least get to ride something without an upcharge." So they need to stabilize the standby experience to get people to distribute themselves somewhere other than the MK.
Because also unlike what other people think, I don't think this change is going to result in significantly shorter standby lines, but the posted wait might get back to the +/- 10 minutes, and not "it might be half of this number, or it might be double, depending on LL usage."