you prefer it on the bottom is preference, I happen to prefer the left analog stick on the top. but that again is preference. the D-pad on the Dualshock 2/3 has been superior since the first xbox and people who prefer the xbox layout have complained about the D-pad for a long time. but that isnt because of the layout.
no the position is preference. the whole reason the d-pad sucks is because of that large piece of plastic between the dpad and the rubber conductor. don't believe me go search for what's inside the xbox 360 controller and have a look at the d-pad assembly. the evil dpad makes a huge difference because it turns that lacking d-pad into 4 buttons making it more acurate.
microsoft used the same design for that dpad that they started with the duke, it wasnt well thought up design but since they were rarely using it nobody noticed till they tried to use it on games that made better use of it like fighting games and fps
