Well, multi-monitor setups aren't often playing games on both monitors (or even all 3, in cases of triple monitor), so that's probably why. Most people with multiple monitors use the extras to watch videos, read, show walkthroughs, chat, or any number of other things. If all three are actually used for the game tho, the multi setup is definitely more demanding.
I haven't looked much at 1440p monitors recently, but I do know Dell makes some very nice IPS monitors in general, so I'd offer those as a suggestion.
ok cool the Dell Ultra Sharp 30" is the second one on my list of 1440p monitors.
That one is a 1600p monitor.
Oh you're right. I didn't even notice that. I was only paying attention to the 2560 --- Oh, you thought they made this game for you? You clearly bought the wrong game.