GBX probably couldn't fit enough of a game into a script that was very intricate...so they had to go with something more simple in the end. The overall quality of the game matches the overall quality of the script when you think about it. I'm sure that GBX's investment in the project squandered any good ideas that the original writers had going into the project.
No commitment to level design, cut scenes, or even finishing the game = your game will be crap in writing department too. No way around it.
The saddest thing about the game is that is sold very well despite it's quality...that's a message to other game companies to follow suit and do the same thing.