"You can't print and bind books!"
"You have to order paper and ink!"
"Printer paper and ink are much too expensive!"
"The printer you buy will become out-dated too quickly!"
"Home printing does not leverage economies of scale!"
For something you can pick up at the supermarket for a few dollars that requires a lot of printing/materials (a book) it doesn't make sense. For something you can't (custom items, small parts, little toys, ...), home printing is (or will be) great.
3D printing doesn't have to meet every use case of commercial 3D printing to become very prevalent.
Custom items? Order them online (if they're semi-custom, e.g. a standard T-shirt with your custom text on it) - it takes less time and will probably be cheaper, despite the shipping cost. If it's a custom item you're 3D-modeling yourself, that's a different story - but that's for hobbyists - it won't be mainstream.
Toys? So instead of picking up that $5 doll in the supermarket, busy parents will find something online and wait a half hour while a noisy printer prints a product which is even more expensive than the $5?
Toys.
Barbie? Probably not.
There's also an implicit assumption here that the design of objects will not change to support their production method. So, if we're limited by size or number of materials then designers will adapt to those constraints.
Currently the number of materials you'd need to stock in your home to be able to print various kinds of products would be quite large (20 or more). That doesn't make sense from an economic perspective.
Let's image, then, that we'll see products made from fewer raw materials because the design changes to accomodate printers. What reason would designers/manufacturers have to do that when they know they won't be able to make a living when their products get pirated?
Look at it logistically - if the cost of transporting bulk finished goods rises to a certain point, it makes more sense to just ship containers of plastic pellets, via slow and less reliable methods. Then local caches of the pellets are used in local printing facilities to make whatever. I can order a part, widget, or doo-dad and pick it up anywhere, or delivery by guy on bicycle happens, or whatever.
3d printing just has less waste and shipping overhead than making goods and sending them to a destination half way around the world.
There are price points where 3d printing makes more sense logistically than injection molding. I don't know what they are, but basic logistics suggests it is true.
Your raw material issue is slain by the same slingshot.
The rest of the argument kind of falls apart after that. No disrespect intended.
