They are scaled up so they have a purpose, no one can throw a grenade 450m or hit anything with a LAW at 725m either. If they only shot 500-750 they would be useless at clearing those random infantry in the little farmhouses on a lot of maps because the LAWs would outrange them.
This has been done to death on other threads, but just to counter that point. M203 UGL grenades could get hits at 300-400m so not far off game range, though more effective at 100-200m range obviously. Likewise LAW/RPG can technically fire out to 700+m but again realistically hits at around 200-300m is best.
However with flame tanks its not a question of accuracy at range, they just shouldnt be able to pump napalm over 1k by any stretch of the imagination. Still the biggest (in fact pretty much the only) thing that bugs me about this game.
out-range them. I don't buy into the argument that physics should be bent just in order to make flame tanks useful. At least give them equal range to LAW, they will still be able to fire through woods and buildings ignoring line of sight anyway...