Only that Hotmail has been much improved recently and even got a completely new design with Outlook.com. Also, care to elaborate on what "much better ones" there are? I barely use Facebook while Twitter is essential for me, but I don't see a better social network for most people than Facebook.
e-mail account is different, as it gives you an address that others will use exclusively to communicate with you. On the other hand, Facebook friends will use your name and the search field to look up for you, unique address is not that critical in such infrastructure.