Uh, users normally cannot install software on a business machine. They are part of a domain, their users do not have administrative access - installing software is not infrequently against company policy. Its not exactly uncommon that these machines cannot even download patches for themselves, those must be administered by a WSUS server. In addition, these machines almost never have a discrete GPU (complete waste of money in these machines), normally possessing solely an integrated GPU. Why not support them? Because doing so costs, and the resulting income would be far smaller than what you could get by expending the same cost against the "mainstream" system base. As has been much of the point in the discussion, had they concentrated on DX11 support (thus dumping XP) - then any system with a DX10 or DX11 capable hardware would run the game more efficiently. Whether those be low end systems, or high end systems. WoW didn't implement its D3D11 renderer for strictly graphical reasons, Blizzard did it to make low end hardware run better, and that work still made high end hardware run better too. It also removed certain restrictions on settings (D3D9 cannot mix types of effects).