Subway Map (Re)design

Above: The Tokyo Subway Map.

Not being fluent in Japanese, it must be said, I find this map very confusing however I assume that for a resident of Japan, it must be easy to understand. I make this assumption because the above map follows all the rules laid down by Harry Beck in 1933 and followed by Massimo Vignelli in 1972; The various lines are represented by different colours; the lines are all at 45 or 90 degrees; each station is represented by a box (rather than a circle, presumably to accommodate the form of the Japanese symbols); and the appropriate geographical liberties have been taken.

Are these the unwritten rules of railway map design?

Korean designers Kim Ji-Hwan and Jin Sol plan on redesigning underground maps from around the world starting with Tokyo, Seoul and Osaka. According to them, each cities subway and railway structures should reflect the character of that city in some way.

The above image shows the intricate network of Tokyo's subway, lightrail and monorail with over 1500 stations covering the metropolitan area.  The centre of this map has the Imperial Palace, and the subway lines circumvent the grounds that surround (are claimed by) it. This characteristic is visualized in this map by the concentric circles spreading outwards through the city. This representation of circles is suggestive of the Japanese national flag and the subsequent Japanese identity expressed in the flag. 

I think it looks great, yet I can't help but wonder if a stronger suggestive visual effect could be achieved if the map was made white. I'll do a bit of photoshopping on this one I think, I'm too curious.

White background. Is this another unwritten golden rule of map visualizations?