Bioprinting an organ takes hours, which is not so good for mass production but just fine for custom organs.

I see your point there. I guess unless you had way more than would be good than it is note efficient to print.

Nanobot swarms would act at the speed of bacteria, so crafting an organ with them could take months. You're right that it could be less invasive than surgery, but it would be slower. They're still interesting because they could do things that surgery and bioprinting can't do at all, like ongoing maintenance of some kind.

The preventative maintenance side is interesting, because their maintenance would be a lot more efficient than the bodies healing process, plus they could heal things our body couldn't, or be able to heal life threatening damage as it happened (burst vessels and such).

It's probably mostly because of how small and thin they make them. Maybe someday Nintendo will make a smartphone as resilient as their old 8 bit controllers...

Those things could definitely take a beating. Ah the good old days. I've read that part of it is how small the components are that make up the electronics that cause them to be easily damaged, but I think we could make things smaller and tougher. It is just more profitable to make things that people break and replace

Like I said though it wouldn't have the same sensitivity. We pack an awful lot of sensors into our skin, and our nerves are able to bring all that information back to our brains somehow.

http://www.iflscience.com/technology/smart-artificial-skin-could-give-prosthetic-limbs-feeling Kind of like this

Bones are harder than the same weight in steel. Muscles are also surprisingly strong for their size and weight. Brains do an amazing amount of processing for very little power consumption.

But they are structurally weak. It can withstand a lot of pressure dead on, but at an angle it takes a surprisingly small amount of force to crack or break them.

All of this repairs itself enough to last 70 years under conditions where everything else falls apart much sooner. Everything rusts, hardens, softens, wears out, and eventually fails.

With the right setup and by slightly over engineering things we can make them last longer. It just isn't practical given the rate at which technology improves.

We're now learning to do external repairs and maintenance on our biological systems as well, including activating built-in regeneration. It's just too bad we didn't come with a manual.

It would make things so much simpler. Although the manual would be the longest most complicated manual ever.

You forget all the sensors, actuators, and small motors needed to perform comparable tasks with high dexterity. More complex mechanics are also thinner and more fragile.

You are right. I was only thinking of the main parts, or bones, not the things that make them move. I think if we did more of a pneumatic approach (sort of like muscles) instead of motors and servos we could make them a little more durable.