I think not everyone needs a network adaper or a hardrive. not all games are online you know?
and the hardrive in some cases would have some benefits that are not related to the network adapter, so it actually can be bought separatly, like in the case of some games making extra use of the hardrive for larger worlds.
but it is true, the best use of the hardrive is with the network adapter, to download demo games or movies.
another use of the hardisk is for the development on PS2 with linux ( but i am not sure if this will release stateside or not ).
as others have said, the price of PS2 will reduce, propably around 30% if not more. and this will make it in the same range with x-box ( 300$ with network and hardisk ). and it\'s true that sony will have online games this year, while x-box is planning for 2002.