It's actually just clever marketing: they're offering a risk-free entry into nerddom. Any of us who have ever thought about any kind of computer-based project reckon that we can now do this with one of these ridiculously cheap devices as opposed to possibly repurposing existing hardware. Selling it as a barebones kit is just as clever: you still need a power supply, SD-Card, screen, keyboard and mouse to use it but you think you can just use existing equipment for this. This is pretty much the same as "low-cost" airlines. I'm not saying this to have a go at the Raspberry Pi, just trying to explain why we find them so irresistible. And why, while some people go on to make amazing projects with them, others have them lingering around along with foreign language courses or gym memberships.
So, of course, I've got one (running XBMC/Kodi and not entirely without problems). To get an idea of the power of the device I also ran some CI testing of some software on the device and was surprised to see it running 10% as fast as my 2009 MacBook Pro, which is impressive at the price. Configured correctly, a couple 2πs could make local CI a reality for me.