It's the content holding back the revolution. That, and printers are still pretty crappy and still improving quickly. Making original models from scratch has a steep learning curve...it takes skill to use 3D modelling software. Handheld 3D scanners aren't cheap enough or good enough to make it worth having a 3D printer for the average toaster user. (and even with a good scanner, you have to clean up the model and modify it for printing). So, while 3D printers are fantastic if you have the skills to use them, it's not easier or cheaper for an ordinary person to use one versus just buying a part produced by someone else. And that's not even getting into the nuances of different print materials your printer can use versus the quality industrially molded plastic or other processes put out for less cost. I personally use my printer to make wargames terrain (toys), but a) I have the skills, and b) wargames stuff is expensive enough that it's often (but not always) cheaper or easier to print stuff, and I can customize the prints. It's kind of like saying that CNC router tables and/or laser cutters are the bomb for woodworking. Yep, they are great, but at the end of the day it's just another tool with a relatively specialized use in crafting. When we have a process that can scan and print copies of an object, at 1 micron resolution, at the push of a button, in under an hour, then it'll really start taking off. Because until that point, it's not really consumer ready.