You know what's holding 3D printing back? As someone that's fighting with one, I've got a few thoughts.
I'm building a Prusa Mendel, with hardware mostly donated by a friend that also has a Prusa Mendel. It *should* be straightforward. It's not. At all. My friend and I got the frame built, but I brought everything else home to finish on my own.
I managed to get the mechanical end sorted out fairly well, to the point where I need the entire printer to run right to get the rest of it dialed in. I managed to get the software side sorted pretty easily, too. The electronics, however, are proving to be a major pain.
The machine has a few problems that I can not seem to sort out. The hot end temps vary wildly, in about a thirty-degree Celsius range...However, it's all built "right." At this point I'm going to build a second heatcore and replace the thermistor attached to the nozzle with a new one (that I had to order from somewhere else) in hopes that something is wrong with either of these two items.
I am proficient with electronics assembly and repair, to the point where I build my own pedals to use with my bass, repair my own bass gear, repair other folks' pedals and gear, etc. I do computer software troubleshooting and programming for work, so I'm fairly proficient with that. I'm also a hard-core gearhead; I've been playing with mechanical things from guns to cars to motorcycles to machine tools and just about everything in between for as long as I can remember...But I'm having a hell of a time sorting out a *basic* 3D printer. I've spent the past three weeks of weeknights and weekends working on the thing and, honestly, I'm about ready to throw the whole pile in the trash and forget the whole thing.
It doesn't help that no one local to me has any more experience with building these things than I do, and all the people that have pre-built 3D printers are also hating them right now...My old employer has a MakerBox Replicator 2X that they can not get to run right. It seems like the vendors themselves don't really know what's going on, either...The vendor I got the hot end parts kit from seems to supply wire that I would consider wholly inadequate for moving 12V@5A around, but apparently it works.
The guy that supplied the parts for me to build my Prusa Mendel purchased a Rostock kit for no small amount of money...And is having all kinds of trouble getting it working right, too.
What's holding back 3D printing? The fact that even people with higher-than-average technical proficiency in all the areas required to make a 3D printer run well are having problems with their 3D printers indicates that they are in no way ready for mainstream use.