Why can't I pick up blue item without them binding to me?

Answer 1

It's not that it's blue per se, it's called BOP vs BOE - bind on pickup and bind on equip. The highest level items are not meant to be auctioned off - they take too much time and effort for someone to run kara a 100 times then be beaten by a newbie with their own weapon when the newbie buys gold off eBay . This is why there is a loot process - because some items are bind on pickup, we want the people who can actually use the item right then to help the party right then. If no one can use it or it's not as good as they've got, sometimes an enchanter can disenchant it or there is a 'greed' loot roll.

Blue items are rarer than green (often higher power and even more often more durable than a similar green object) so they are more likely to be BOP. Purple is even more likely to be BOP and Orange (legendary) appears to ALL be BOP.