A large number of Facebook users expressing discontent about the new layout reaching 3.8 million between two Facebook user protest groups, Facebook CEO Mark Zuckerbergresponded in the Facebook company blog:
It’s tempting to say that we should just support both designs, but this isn’t as simple as it sounds. Supporting two versions is a huge amount of work [...]
Users will be able to start exploring Facebook in the new layout starting the week of July 14. Unlike the developer sandbox, which has been restricted to only allow access to the new profile page, starting next week all pages will be available to users in the new layout, including the home page, News Feed, [...]