There are a number of people who need two cards to get the settings they desire and have decent FPS. There are still a few games I can't max out with two 470's, quite a bit more when you count 3D vision. There are no single GPU's out there that can perform at power of 470's in SLI.
There are others who use 3 monitor setups, and still others with 2500x1600 resolutions.
Can you run games with low end hardware at low settings? Sure you can. Can you be happy about it? Sure you can, but that doesn't mean there isn't a wealth of higher end settings and games right now that could take the power of GPU's faster than what we currently have.
Also, even for those who don't care about good looking graphics, you might be happy to learn that with every new generation, the older generations are sold at very low prices allowing you to upgrade at a good price. Everyone wins.
One last thing, for those who believe FPS in the 20's or 30's is acceptable. This is not considered playable by many people. Some people even experience motion sickness, eye strain and headaches (I get motion sickness). You may also be surprised at how much smoother and reactive games are when FPS are over 40 (and over 60 FPS with a monitor that can handle it is smoother yet).