That's actually my biggest complaint about 3d printing...
It's never going to replace injection molding for manufacturing. That will always be cheaper. where this comes in handy, is prototyping. which is what they were intended for from the beginning. you need to make a part, a one-off... it's great for that. if you need to make more than one... then other options are available. but to be honest making a SINGLE one-off part through injection molding? that'll take you more than 50-100 times more electricity of the 3d printer, because you'll need to make the mold, and then you get to throw it away because its not needed anymore.
but for prototyping and one-offs... thats where 3d printing's niche is. prove it can work with a 3d printer, then mass produce it.
now since this article is about METAL 3d printing, that's an entirely different beast altogether... injection molding (Casting) of metal components of course will be cheaper, but can you cast multiple alloys together like this? that's kinda cool... even you gotta admit that.