Here's something that you guys may not know. It's actually a topic discussed here and on all message boards.
The USTA prides itself on the Open being the toughest, most demanding of all the slams to win. At the Open, you face extreme weather changes (hot, humid, cold, rain, wind), night matches, the "New York crowd" (which has really been wussified since Ashe was built now that the rowdies sit a thousand miles from the action), and Super Saturday with the final on Sunday. It's for this reason they won't build a roofed stadium.
People say it's Roland Garros. People are wrong.