The comm has the same responsibility as the GROUP of marines on the map, you cant single out the comm as being the same importance as one marine. Commanders give you your res towers, tf's, meds, ammo, ect, while soldiers out in the field have to build and shoot, yeah, i think comm's are a bit more important than the soldier. For the simple fact i commanded a game with only 2 marines vs 4 kharra, the entire game, and we won. Now the marines i had we're not LM regs, they weren't that great at aiming, and didnt go to their waypoints half the time, but since i was comm i gave them meds, an rt i thought would be valuable, locked down seige locations, and finally took down the hive with heavy weapons.
Whoever steps in the commanders chair should know they are as important as the GROUP of marines on the field, not just one or 2 soldiers. To say the comm is important only to a beginning extent is a bit, well, in my opinion not true at all.
Mid-game the comm has a very important role, usually at this point there is at least 1 or 2 fades, a hive either going up or being MC rushed, usually you cant just send your rines a wp there and have them run in, almost all the time that happend marines end up loosing. If the commander doesnt have a plan on a seige or sg rush attack or such, the soldiers are basically just wandering cattle for the aliens to gorge upon.
IMO thats what makes the marines in Natural Selection so fun to play, the commander is as important as ALL the soldiers on the same team, and if BOTH dont work together, well, the kharra will have lots of teeth to floss.
Remeber, the Commander basically has the most strategic plan to unfold, the aliens all decide together, where as the comm does not, and sends HIS or HER waypoints for the rines to follow, followed by a usual structure drop.
Just remeber to always drop us meds and ammo when we ask.