I might be taking this a little too personally but ranged friendly fire is normally the fault of the person who was hit by it, now, don't get me wrong, there are loads of times I have fired into melee and hit my teammate, ironically it's normally 5 to 1 odds against my ally, the soul reason for me shooting to help him out but in reality, the main reason we don't have reflective damage is because you don't want to punish the better players in order to save a peasant.
For example, if I shot into melee where I hit an allied peasant, with no reflective, i'd kill the poor bastard and have more of a chance of taking out the enemy with a sorry shortly followed, yes i've ruined that guys game, but he will get over it and he might even get a multi for it while if it was reflective, it would have killed me, the peasant would have stood no chance and had his arms ripped off by the angry flamberge wielding, pot helm wearing, dagger throwing strength ninjas and there would be less of a chance for the team to win.
It's the same for melee, as people have said, more team damage is done by melee than it is by ranged, therefore, if for example, lets say... Tor... He swings and a peasant dives in the way, he gets the epic damage from his ridiculous axe and cuts himself in half, yeah, peasant gets away fine, ripped apart by the enemy while Tor can't go on his 10 kill streaks.
Not a great idea, reflective is a good idea in theory, but bad in practice because it punishes people who don't deserve to be punished.