I don't know anyone, or heard of anyone, that can focus on an open window while opening the Win7 style menu to open another program. If you have several program windows open, you can't focus on more than one at a time, you can glance back and forth.
When you open the Win7 start menu you focus on it for a few seconds, open a program, then focus on it or another program/window.
When you open Win8 start screen you focus on it for a few seconds, open a program, then focus on it or another program/window.
If you prefer the Win7 style menu, that's your prerogative, but I can't agree that Win8 start screen takes anyones focus away from their work more than a Win7 style start menu.
I use the desktop +98%, have always pinned most used programs to the task bar, use a program dock to have quick access to other programs I regularly use (and still do this now), I consider the Win8 start screen another dock.
A large percentage of advanced users have always customized their desktop, if they can't get it the way they want with Windows options then they use third party apps.
When MS adds too many programs/options they get sued for being a monopoly/unfair trade practices.
It is not possible to have every conceivable option available for every single user. If/when they try, they get complaints about a 'bloated OS', they will never be able to please everyone.
Try the new OS, customize it the way you want, use third party programs if you need/want. If you still don't like it, use a previous version or other OS. Choice is a good thing.
When at work use what is provided, use other programs if needed/desired, if they are not allowed then lobby to get them approved.