Its simple, the Source engine still gets its roots from Quake. While it has a whole lot of nice new gimmicks ( Skyboxs, Face poser, physics, shaders ) the actually levels are still bsp based.
Building a map for WoW would only consist of laying down a high map and placing the building models onto it. Much like the editor for Morrowind. Where Half-life 2 requires you to hand make the buildings out of brushes taking up more memory.
What it comes down too is the two engines are completely different from each other but I know what your getting at, I was hugely disappointed with the way Half-life 2 handles its levels. 40 - 45 minutes to compile a tiny map ( from today’s standards ), gees this isn't 1999 anymore, no one wants to wait that long to compile a map.
This comment was edited on Feb 3, 12:59.