No reason not to, rather many reasons to do, depending on your situation. With floating static routes, I have found it useful to NAT to the loopback interface. Once I had trouble with a router coming back up, as NAT translations were not clearing. I NATted to a loopback there too.
Sometimes you may want to manipulate DR and BDR selections in OSPF---a loopback with a higher IP address will do this (DR).
Since the interface is always up, it is also good as a management interface (easily managed this was---organize by, say router 1 =1.1.1.1/32, router 2=2.2.2.2, etc.).
My 1.5 cents...
/
tim@tim-laptop ~ $ sudo apt-get install windows
Reading package lists... Done
Building dependency tree
Reading state information... Done
E: Couldn't find package windows...Thank Goodness!