^Actually, the term drag comes from the main street(s) of a town (Brandon Blvd, Dale Mabry, Fowler, etc.) being called the main drag. When people raced there back in the day, they started calling it drag racing, since the only racing prior was done on the tracks. Has nothing to do with starting from a stop.
Dig racing requires more skill and setup. You gotta prep your car more for digs, and some cars just plain aren't good for it. Not to mention there's skill involved as far as throttle control and quick shifting and maintianing a straight line.
If you're going from a roll, any car can do it, really. Also, it's more of a motor comparison being that traction is not an issue (90% of the time), and chassis setup really has nothing to do with it. It's also much easier to shift/hardter to miss a gear. If you're not into drag racing and don't want to set your car up for it, it's much easier to race a car from a roll just to see whose is faster, without driver and rubber factors coming into play.
I don't know why everyone likes to get so tied up about it. "____ racing is GAY!" "Rolls are for pussies," "drag cars can't turn." Not everyone wants a drag car, and not everyone is good enough to go from a dig. If it makes you feel better about yourself because you got a 2-step, DRs and great launch practice, then fine, but calling someone names because they just want to compare engines is childish.