I mean, the most expensive option and the cheapest options are both still available, so I'm not sure a price increase would necessarily work here. If we were to follow the rules of supply and demand, we'd also need to lower the Inspire key costs because they have excess supply compared to demand.
You can't raise the price of the cheaper Believe and Enchant keys without also raising the price of the Inspire key, unless you want to give those two keys more perks to compensate which seems the opposite of what Disney normally would do. The better option from a business standpoint, which is the one Disney seems to be doing, is to limit the number of those passes available to push people towards the more expensive option, thus artificially creating demand and increasing their profits.