Quoting: Erathoniel
I don't think so. In real-time mech games, lighter missiles work more like guns, and heavier missiles usually work like artillery. More physically accurate, too.
Well, not in GearHead.
There's a decent play-balance argument for things being the way they are.
Weapons in the missile class get bonuses to hit based on a mecha's SE rating instead of TR. Since TR is normally capped at +0, while any headed mecha can be upgraded to SE +6, this would make low-DC missiles very attractive to a Mecha Gunnery-only pilot.
At present, I don't find Mecha Artillery to be worth the skill slot. So it would be bad for play balance to make that decision even easier.
As to arguments from realism, I'd say that we'd need to make a distinction between unguided rockets and guided missiles.
The former should probably be considered MA regardless of DC, since they are much slower than bullets or laser fire (by the same token, the Longman's DC20 laser should be MG -- but play-balance again...).
The latter type (di-di-di-di-di-di-DOOOOO whooosh) really should use neither MG nor MA, but Electronic Warfare. With such weapons it doesn't matter if your aim is sloppy -- what matters is whether you can beat your opponent's jamming.