My question is why are the pin numbers 9 8 4 5 6 7 and not 4 5 6 7 8 9 ?
Because thats the way the manufacturers chose to wire the shield. Only they could answer that. There wouldn't be any reason they couldn't wire the shield like that so that it conformed to the liquidcrystal library.
One of my projects contains the line :
LiquidCrystal lcd(12, 2, 7, 8, 9, 10);
I chose those particular pins, because they could be spared on a pre-existing project and because they were easy to wire that way.
I have another project ( http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1260399444 ) that contains the line :
LiquidCrystal lcd(3, 4, 8, 7, 6, 5);
It was because the hand made stripboard arduino board was easy to make with the pins wired like that...........