There's definitely still huge value in the newsworthiness of the launches. Apple get a lot of free media coverage, and for the most part the press treat the actual launches as news because that final official confirmation matters much more than tenuous leaks.
But I often wonder if the top down focus on secrecy and the famous leak prevention programs are more motivated by the strong desire for focus. One of the challenges of keeping a big company effective is combating the tendency for well-meaning collaboration and suggestion making to turn into sluggish bureaucracy and committees. Secrecy a very powerful tool in optimizing a corporate culture, and reminding everyone that it is definitely not ok to share things has that big benefit too.