Scrolling down from the top post will reveal a “Solved” mark with a link to the updated post, which is where the main discussion taking place. The FFlag for the beta link will soon be updated probably to fix the issue you mentioned anyway.
Even though this is not the finalized design, this version is the closest version we have to the final. Therefore if Roblox wants people to get used to the UI more smoothly, they need to release the beta to a broader amount of people by enrolling people automatically to the beta.
If they enabled the Beta closer to the initial release, people would have less time to adapt to the UI.