Why is Disney offering this option now?

Beginning last year and continuing into early 2019, Disney started hiking prices. And though this raised a few eyebrows at the time, Bob Iger said in several interviews that he didn't believe that Disney had a pricing problem, and guests would show up in droves to experience Star Wars: Galaxy's Edge, no matter what. However, when attendance at Walt Disney World and Disneyland plummeted in summer 2019, many wondered if Disney did, contrary to what they had previously said, have a price problem. And though no executives would admit such an issue, some are wondering if this new ticket type is a tacit admission that Disney's current pricing structure isn't working. 

There's also the issue of Star Wars: Galaxy's Edge, which failed to attract large numbers of guests at Disneyland, causing speculation that this new land could fall short of expectations at Disney's Hollywood Studios as well when it opens in just a few days. Disney of course wants to keep that scenario from playing out at all costs, which may be why they hurried this ticket type shortly after their attendance report was released, and have made it available immediately and able to be used to visit Disney's Hollywood Studios. 

Regardless of the reason why, it looks like Disney will be offering this ticket type as a trial balloon of sorts to see if they can get more guests to the park with lower prices (and a few restrictions). And if it is successful, we will probably see even more discounts and deals in the future as Disney tries to stealthily roll back their price hikes in an effort to get guests back into their parks.