Unless the share price is hit by the backlash, the new passes offering will not change.
One good news article pointing out the loss of customers over this change would shake the share price.
Don't forget Merlin are now a private company. There's no share price to shake
The initial intention of the passes was to increase guest numbers and encourage people to spend more. Sell them cheap and have people spend more time at the resort, using accommodation more, buying food and drink more as they see a perceived value from the pass being so cheap that it's worth splashing out.
As a public company, increasing visitor numbers became a key metric of "success", and it seems revenue per guest became a secondary factor. Passes got cheaper and cheaper, and like the myriad of 2 for 1 offers, the product they were selling became increasingly unviable at that price. Then in rolls private investors, and of course Covid and now it's more essential thanks to lower guest capacity that they squeeze more money out of each guest.
A pass-holding family turning up with tin foil wrapped sandwiches and not paying for parking makes them nothing. Quite literally, nothing. That's not sustainable in the long term. Yes, it's extremely harsh for families who are trying to have a day out with the kids, but Merlin are a business after-all, and with increasing costs from higher wages etc, something had to give.