A nit-pick: I believe most Raspberry Pis sold are the US$35 Model B (or new B+). There is a $25 Model A available that has half the DRAM, no Ethernet, and a single USB port, but they don't sell as many of those since most users would prefer to spend the extra $10 on DRAM and Ethernet. Model A is typically used in embedded applications that don't need Ethernet, especally battery-operated projects that can take advantage of the A's lower power consumption.
I just returned from ESC Brazil where I heard one of the keynote speakers -- Jon "MadDog" Hall -- talk about the Banana Pi, which he said was much faster and had greater capacity and performance as compared to the Raspberry Pi
Why? Cuz I like this direction and it gives the home electronics hobbiest something else to play with! Whereas once upon a time, the "techies" could amuse themselves with the latest PC. More recently, tablets and phones scratched the itch. But now, the difference between newest and 2 generation back products is so small that the curious "tinkerer" is ready to go more primitive and create low cost items that perform very specific functions.
Ok, I'm really talking about myself, but I assume that there are, well, 1.5 million others (I think that's the number in the article) who would also be interested. I have to agree with the final statement. Value is important. But more capability for a little more cash is compelling more the the hobbiest than to someone trying to design something to sell.