I agree that they can be bad at relaying tone.
480p and 720p are video sizes based on standards of DVD and Bluray videos and TV.
When i think of high res (and not the common 1080/1050 vert line monitors) i think of 1200 and 1600 and beyond.
In gaming there is almost always something better: more fps, higher res, more shaders, more anti-aliasing, more dpi, new game engines, etc. So saying only multi-monitor support is what is better isn't entirely true, +edit: because then nVidia would be really bad with its measly tri-monitor support compared to ati with six
What i could say though is that it may not be a large gain for the amount you pay, for eg. the 590 is not a huge amount faster than a 570.
But if you really take that stance, the 570 isn't that much better than the 560... which isn't that much better than the 480.
Where is it that you draw the line?
Your budget is the only really important thing... and sticking to it can be difficult.