Blizzard commented on this a while back. They said they don't expect people to pick up everything, they don't want people to. They have adjusted the prices items sell for so that players aren't going to pick up everything. The reason all this useless stuff drops is because Blizzard likes the feeling of loot explosions. They want you to kill a mob and a whole bunch of crap drops everywhere.
In Diablo II, there were some white items you really wanted to pick up anyway, just because they sold for a good chunk of gold, but I'm not sure if we'll be seeing that in Diablo III.
White items will not be worth the inventory space. No one will pick them up. If people start picking them up we'll reduce the meaningless amounts of gold they already sell for even further. We can address these things if they happen.
In Diablo II, there were some white items you really wanted to pick up anyway, just because they sold for a good chunk of gold, but I'm not sure if we'll be seeing that in Diablo III.
Originally Posted by (Blue Tracker / Official Forums)
http://us.battle.net/d3/en/forum/topic/3932984660?page=3#54