Chemical Weapons on Gaza - Why White Phosphorus?

It has occurred to me that white phosphorus has some of the following qualities, particularly useful in urban warfare:

1. It is absolutely terrifying with the result that the populace will flee before it - great for inducing panic and herding a populace away from an urban area when preceeded by leafleted warnings
2. It is absolutely deadly and perfect for denying territory to your enemy, laying waste to property and clearing bunkers and tunnels
3. It doesn't seed the land with unexploded ordinance like cluster munitions do, thus making the land unuseable for months and years afterwards; great if you want to settle there afterwards
4. The smoke screen effect (especially useful at night) makes it almost legitimate to observers from afar...

This link has proved interesting: http://www.dailykos.com/story/2005/11/9/164137/436