A lot more than 1% of us are using resolutions like 5760x1200 though, and in the absence of proper surround testing 4K is the next best thing for us to look at. If you aren't going multimonitor (or 4K) both the Titan and 290X are overkill.
I agree, and furthermore, those who want to have their fps glued to 120Hz at 1080p or higher will also benefit, especially those who also want 3D. Or alternatively those who want Surround and 3D.
If you add up all the Eyefinity/Surround users at 5040x1050 or higher, all the 120Hz 1080p people, all the Surround 3D people, and all the 4K people, in the next 18 months, that is more than 1%.
The 290X is not aimed at people with 1080p and lower monitors anyway. If you are happily gaming away on your 1080p with a HD5850 or GTX560 or whatever, good for you, but you are not the target market for this card.
In any case, I'm glad that GCN seems to take less of a hit as you scale up, relative to Kepler. That's a good sign for longevity. Remember that PC gamers get tons of console ports, and consoles are based on GCN. The longer the legs of GCN, the less watered-down stuff PC gamers have to put up with.
P.S. If my math is right, 1920x1200 x 3 is 83.3% the pixels of 4K. Good call on that.