[Aj_]

That change in the camera system was followed by a delay.

1. A fundamental change in the graphics engine would result in a big delay, you'd most likely have to reprogram, reproduce, and redesign models and textures through out the game.
2. A overhaul of the interface would affect the gameplay, if you had to change how the interactions worked you'd ahve to test the whole game again.

Testing should take place on alphas when the principles are set in stone, and beta when the content is there. Testing takes a very long time. Adding new features means you have to test the features, and test all the interactions those features have with what you already have in place. An overhaul of something like the interface or graphics would require complete retesting.