My praise for the new Need/Greed system may have been premature. It's been pointed out that there is a moderate flaw in the system
Consider the case of a player who rolls Need on everything she can, regardless of what she is currently using. Under the new system, that player will prevent a off-spec character from getting the item. Under the old system, the off-spec character at least has a chance of getting the item.
So it's a trade-off, I guess. Under the old system, a rogue player has a chance--it's not guaranteed--to take main-spec items from you. Under the new system, a rogue player can guarantee that you won't get any off-spec items at all.
Of course, there is a work-around. If you really want gear of a certain role, queue as that role. And guaranteeing the main-spec items you need is probably the more optimal outcome.