Not needed at all and it's a good thing.
You don't need this DLC to play game at all. It doesn't has any feature that playing without makes game unplayable, but it has a lot of small ones that can make your games more in depth and allows for more freedom in your game. The big features of this game as of more depth to Middle East and army professionalism don't make this dlc worthy in itself. What makes it worthy however is making small changes like promoting advisors, exploiting development or allowing to use missionaries in your vassal provinces. From big features exploting professionalism serves good as additional manpower pool and it buffs Mameluks, so Ottomans don't have so easy start for their blobbing