Why? The first and very obvious reason I see is that I will need to access my files stored in my own SkyDrive account while signing in as a domain user. Also, I can have my apps, passwords, and personalized settings got sync’d automatically across all computers I am using.
How? It’s made extremely easy in Windows 8.1, and you can get it down in a few steps.
Go to PC settings from Settings charm bar, Accounts tab, and click or tap Connect to a Microsoft account link on the right side of panel.
Now you get the options to pick what’s got to sync and what’s not. Select the items you want and go to Next.
Now sign in with the Microsoft account you want to link, follow the instruction on screen to get a security code to verify your account.
Once all verification is passed, bang, you are all set. Do not forget to click the final Connect button to make the final connection done.
Now finally, I see SkyDrive icon shown up in my File Explorer under my domain user account.
How about connecting LOCAL account to Microsoft account and only sync SkyDrive
here is how http://www.nextofwindows.com/windows-8-1-how-to-convert-windows-live-account-to-local-account/