For those using low resolutions (like 800x600 instead of 1280x960), the pixels are bigger and using anti-aliasing would make these "large" pixels stick out less. A 2x anti-aliasing for 800x600 would simulate the quality as if running at 1600x1200. If running at high resolution (like 1920x1440), there is little sense in using anti-aliasing as the pixels would be very small as it is, but some would still prefer it because it enhances the quality of the scene. In some cases, I'd probably even use a 4x anti-aliasing method which is extremely fine, right next to the limit of the human eye at the highest of resolutions.

I would support having anti-aliasing and it can be configured through the command line like this:

-aa 2

for a 2x anti-aliasing effect.