Sorry to take this thread into a different avenue. I may just start up a thread for this if enough people ask this question.
Onto the answer.
The old levels were apart of the design process. I had to create them to create the later levels. They were just a previous iteration of a level. One of the old levels, the one with the white road, is actually the oldest level we have in the game. That one probably came from first-playable if I remember correctly. It's a level I had to create to get experience with working in the editor and seeing what's possible with it.
The older levels are decent enough to add into the game, but not as polished as the levels that are in story-mode. The city layout, and decoration within the levels were just not up to what I was doing in the later story levels which is why we placed them in the "old level" section of the game.
Some level layout issues exist with the old levels as well, such as placeholder art and hand crafted set pieces that I had to make on the fly. The newer levels have objects that are specifically built for some of these issues. There were also some areas within the older levels that seemed odd gameplay wise, and visually(camera tracking and such).