Maybe WWE has recognized that the success of the NXT format could be transitioned up to the main roster and they're testing it with Smackdown. They've made a couple of changes that support this: fewer PPV shows and co-branding all of them, this leaves maybe 4 matches per brand on each regular PPV. NXT takeovers are typically 5 matches. This gives some breathing room to feuds and they don't all have to build towards a match at the nearest PPV. They can do multi-month builds or focus on doing big blowoffs at the big 4.
Stacking the 2 hour format with main event capable talent will keep the roster healthy, and it will be less noticeable if talent closer to the top takes some time away. WWE had a lot of plans botched due to the health of superstars in the last year, and they'll need to rectify that to keep the product strong. The age of the athletes they're depending on to carry Smackdown has to be at least a little bit concerning. AJ Styles is 40, Nakamura is 38, Samoa Joe is 39, Jeff Hardy is 40, Daniel Bryan is 36, The Miz is 37, and Randy Orton is 38. Clearly they can all still go and put on some amazing matches, but not TV level one-on-ones every week. Less is more for some of these guys and their placement during the shakeup will support their longevity while giving some of the younger guys a chance to get themselves over before they enter the top of the card scene.