Lacks native support for many languages and scripts.

Javascript, HTML, CSS, XML, SQL etc …
A convenient built in means of compiling on a remote machine while being able to edit locally and run remotely but view locally using xcode.
For example, be able to use a low power Macbook 12 for local editing and compile and run all the code on a more powerful remote Mac Pro, while being able to see the app running locally on the Macbook 12.
Compiling on a Macbook or Macbook Air is NOT a good experience, though their portability is great.
Also helps in maintaining servers.

Observer2010 about Xcode