In designing our Lync 2010 environment, I was a bit beside myself at the scale of the number of required servers to deploy a simple, yet redundant, environment. Even cutting a few corners, we ended up with 13 servers for our Lync pilot. Using the same design in Lync 2013, the total number of servers is only 9.
Lync 2013 simplifies the back end database requirements by storing data in the front end servers, one of which acts as a master. The remaining front end servers act as backups, and will automatically take over in the event of a failure. For this matter, Microsoft suggests deploying a minimum of 3 front end servers for a scaled enterprise deployment.
Director, which has always been optional but recommended, can also now be ignored altogether. See the technet supported topology documentation for details and more information.