>On a brand new Windows Server 2008, we need to install SSMS only from the SQL Server 2012 CD. Can someone explain me why it requires .NET Framework 3.5 to be installed? Or, is it a problem we are facing? This OS is installed with 4.0. I don't feel comfortable to install 3.5 just to have SSMS running.

From this : http://msdn.microsoft.com/en-us/library/ms143506.aspx (Hardware & Software requirements) it looks as if you will need both 3.5 SP1 and 4.0....