"Thus far, 3D printing has been used to make shapes of plastic or metal that can be assembled later."

This is incorrect. There is at least some 3D printing technology today which makes it possible to print at least basic mechanical parts with no assembly required. Here is a video demonstrating its use, printing a working crescent wrench (including the worm drive for adjusting the size of the grip):
http://www.youtube.com/watch?v=ZboxMsSz5Aw

Amazing, no? That said, the idea of printing out variable-density concrete and applying the technology to large-scale structures is pretty amazing too.

Having worked in social media and social gaming quite a bit in the past, I've heard this and the other side of the argument on "social gaming" many times. Yet no one, on either side of the argument, even those active in the industry to this date, have actually admitted that they themselves play "social games" such as Farmville or Cityville. They have no desire to play the very games they create. They tend to prefer games with deeper strategy, storytelling, or action dynamics. Indeed, Smash Bros and StarCraft were far bigger hits in our office than any of the games we actually made.

But the masses, who evidently do like these games, pay their salaries.

I'm not a diehard entrepreneur ready to seize on this particular trend and perhaps make a nice buck from it just because I can. As a software developer, I'd much rather be working on what I myself consider to be rich, engaging gaming experiences. And that's what I'm doing instead. It helps me sleep at night and wake up in the morning just knowing that I work on the type of game I genuinely enjoy playing.

I would have to agree with this assessment. I would also say that people who are less likely to install frivolous things such as extra emoticons or extraneous toolbars from untrustworthy or potentially untrustworthy sources (ads, torrents, or sites requiring an installation for access) are pretty safe.

Adding to that, the Mac community's ecosystem for applications is relatively resistant to these kinds of things. For all the snobbishness surrounding ownership of a Mac, you also have high expectations for Mac applications; even simply the way they conform or deviate with Apple's Human Interface Guidelines actually impacts the success of a Mac application within the ecosystem. This trait makes Mac users in general more picky about what they install. Mac users usually find new software through their friends, positive reviews, or (now) the App Store. They are far less likely to find it through banner ads for free smileys or toolbars.

That's not to say that this won't/can't change. The Mac is also becoming more popular among amateur computer users, such as mom and grandma, as opposed to professionals who use their computer more like a tool than a toy. As this segment of the user base grows, there may well be a correlation with the number of actual Mac malware infections.

For example, Elite Command is a highly graphical multiplayer browser-based game, and it doesn't use any fancy HTML5 features:

http://elitecommand.net/

No flash, no HTML5. Just regular old HTML, CSS, and JavaScript (DHTML, as they used to call it).

Disclaimer: I developed Elite Command.