This is just a guess, but....
Could be that, since those resolutions are in the ballpark of "twice" what you would see in most laptops (2x720p, 2x900p), the high-DPI setting the screens use just makes it a much sharper equivalent of the lower resolution in terms of actual screen real estate.
i7 3820 @ 4.4, Custom Water Loop | ASRock X79 Extreme4 | 8GB G.Skill 1600mhz
EVGA GTX 670 FTW | BenQ XL2420T 120Hz | Samsung 840 250GB |WD Black 1TB | Win 8 Pro x64
X-Fi Titanium Fatal1ty Pro | Sennheiser HD555 | Corsair TX850V2 | Fractal Arc Midi R2