A shiny blue item drops off a boss in a flashpoint that your character obviously can't use, but would be a hefty upgrade for your companion.
1. Need roll
2. Greed roll and 'hope' that you win and nobody else needs it
3. Waste 5 minutes explaining to the other group members why you want this item and decide how to roll/trade for it/etc.
4. Whine like a little girl until whoever won the roll gives it to you to shut you up.
Number 2. Needing gives your companion the same chance to win as an actual player which is not fair. (In my opinion)