I have seen many game developers and CEOs say Windows 8 is terrible for gaming and companies such as Valve the creators of Steam(The main service for PC gaming and developers of games like Counter Strike, Portal, Dota 2, Half Life, Left for Dead, etc.) have considered to boycott the service, the CEO of Blizzard(Developers of World of Warcraft, Starcraft 2, and Diablo 3) have stated that Windows 8 will be terrible for gaming as well. If this truly is the case then why would I upgrade to Windows 8 and why the heck would Windows do this? Also is there really going to be no start menu? Why are they downgrading the service?

The companies say that Windows 8 is bad for gaming cause they fear the new Windows 8 Style UI. There is no proof to back up any remarks that Windows 8 is any worse for gaming than any other version of Windows other than their fear.

Yes there is no more start menu. It is dead after 25+ years.
They are not downgrading the service, they are looking to the future when more devices and PC's get away from the standard mouse and keyboard to a touch display that everyone is so used to with everything else they do.