I agree with you that the fanatical marketing will always make me roll my eyes. I /like/ new technology and processes, though I approach them with cynicism and analytical criticism until they've proved tangible potential. I've used 3d printing for a great many things, even some /functional/ non-prototype parts.
However, I'm not sure why you keep going back to material property comparisons. I don't understand your gripe there, or what you're comparing, in order to get an apples-to-apples idea of the differences.
Regardless of your derision of SpaceX, NASA has no marketing, glamour, or aspirations of changing the industry or shoring up anything for personal interests. Their only interest is accomplishing missions as best they can. So I would take NASA's use at face value. I only use the 'space' parts because it's hard to imagine components under more dire conditions than a liquid rocket engine getting shuttles outside LEO.
There are many other industries benefiting from additive manufacturing. Boeing has been using the process for flight parts for commercial and military for over a decade. Weight saved on aircraft yields significant fuel savings. They also use them for parts in tool making. We have used 3d printed plastic parts for many components when making large tool assemblies for them. This is for projects as old as the Chinook, even, though obviously it's a recent revision, not an original design spec.
Then there's the interesting differential metal sintering that SLS can achieve. There are, obviously, ways to weld different metals, as well as create differential metal stock via explosive means. However, SLS can achieve very selectively placed differential metal gradients. You can have an assortment of different metal properties throughout a part where you want it. It's a design tool for specialty parts, for sure. I imagine it might also allow one to be more selective of very expensive metals or alloys, and place them ONLY where needed, rather than buying a whole piece of stock and removing what you can get to, and possibly leaving it where you don't need it, simply because of the original stock properties.
Back to plastics, the medical industry has a really interesting benefit that a friend just linked me to just a few minutes ago:
Finally, a practical use for 3D printing: Helping surgeons rehearse ? The Register "According to Sherry, the ability to use 3D printed models to pre-bend titanium implants has reduced surgery time significantly..... .....As demonstrated in a recent maxillofacial procedure at Salisbury District Hospital, the ability to pre-bend the titanium plate prior to surgery enabled surgeons to secure the perfect custom fit. This reduced the number of incisions required and overall theatre time, directly impacting the quality of patient care."
And Finally... stop looking reading into these crescent wrench videos. It /is/ a functional tool. No it's not better, nor is it even good at being a wrench. It's just a demonstration of geometry and capabilities. It expresses the ability to achieve a single print with completely internal components that didn't need a weld step, as well as the ability to make a complete assembly after pushing one button. It's a demonstration of ideas. You should know better than to listen to snake-oil salesmen - they exist in metal manufacturing just as much as 3d printing, this is nothing new.
. We make parts with our 3D printers that take several hours to print. We used to machine them on a 5 axis and literally take days! 
