Why does Dragon Age II need 4 GB of RAM every other game only needs 2 or 2.5?

Dragon Age II Recommended Requirements

Core 2 Quad/ Phenom II X3

4 GB RAM

GeForce 8800 GTS 512 MBWhy does Dragon Age II need 4 GB of RAM every other game only needs 2 or 2.5?
It evidently has more things that it needs to store in memory.Why does Dragon Age II need 4 GB of RAM every other game only needs 2 or 2.5?
Because the game is a memory hog. It's a pretty demanding game maxed out.

So what if GTA IV recommends 2.5GB? Every game is obviously different.