I have asked this in the past,
one of the main reasons is that they couldnt handle all the new affiliates that would come on board and be able give each affiliate an “active” affiliate manger who does respond to you in a timely manner.
there affiliate process is not streamlined like other programs (which they are working on) – alot of the process is done manually by the affiliate manager, like getting tracking codes and banners or any other custom stuff etc
for me they are an excellent program
so i think when the upgrade is finished – they may come on board.