“Why would I need those?”
Well, as I’m sure you know, it’s not just about a server operating system. It’s about what that server does for your infrastructure and your business. If a role or feature is installed (and more importantly – configured), you don’t want to have to re-create it from scratch just because you installed a new version of the operating system as your platform of choice.
The Migration Tools provide the documentation and the automation for the sake of moving important configurations from the old to the new server.
And make sure you evaluate Windows Server 2012 for yourself.