Hi nasimson (Talha),
I'm very sorry for not replying sooner. I just missed your comment.
Microsoft conducted an enormous number of tests with Windows 8, including the Start screen. I think Microsoft believes the new Start screen is, in effect, the first screen with all the various sized tiles. Yes, it won't necessarily include every program on the computer, but it will display the most important ones that a user pins to that first screen.
In addition, the applications on that screen can be dynamic -- always updating (e-mail, calendar, weather, photos, Facebook, Twitter, etc.) -- so it could be considered even more useful than Windows 7.
I'm not suggesting that Windows 8 won't be confusing to many users, both personal and enterprise. But Microsoft believes Windows 8 is the evolution to a new way of computing, evolving from desktops and laptops to greater use of tablets and phones, plus desktops and laptops equipped with touch screens and touchpads.
Perhaps Windows 8 is sort of a "bridge" OS between the today's more fixed computers and the future's more mobile type of computing, and Windows 9 will be the version people really want to use!
In any case, we'll see in another six to 12 months just how popular Windows 8 is.