As far as why they broke the strip up...Im guessing due to framerates or something of the sort. Maybe the game just ran like crap with the whole strip at once.
I have to say im pretty dissapointed the strip is broken into sections like it is AND the New Vegas part of New Vegas is really small and not where you would need to spend a good amount of time. Fallout 3 had DC, and was centered around DC and it felt important to SO many quests with so much to do.
New Vegas, not so much.