"Why the big image?" This pixel art was designed so that it displays its proper proportions with non-square pixels (in this case 4:5 width to height ratio). This allows for some level of greater detail, kind of like a higher resolution. This technique can be observed in Capcom's CPS arcade board titles such as Street Fighter 2, in which a resolution of 384x224 is displayed at 4:3 on a CRT.
Left image uses non-square pixels with correct proportions, right image is unscaled image with incorrect proportions.