Would removing the melee lunging fix the melee vs range issue without destroying melee's damage or buffing range to become gods? I don't see a real down side to removing the lunge at all.

Keep in mind that players tend to back peddle when against a melee opponent.

Removing melee lunging removes all usefulness against someone with a ranged weapon. If I can't hit you because you're backpeddaling and can just mow me down with a bolter then that's not a balanced fight. Right now the biggest issue to the melee vs range problem is how defensive bash works, or rather, doesn't work.

The Developers if I remember correctly actually tried something like this way back in the early alpha and it horribly backfired, that patch will forever live in infamy as the day melee died(thank god they changed it back)

I dunno about removing it, but it would be nice if it were more under player control. As things currently stand, ranged classes are barely rewarded for dodging/rolling away from a melee attacker because the stupid Z-targeting system combined with melee lunge just automatically tracks them and mindlessly carries the melee player into kill position. If the melee player had to aim a lunge to catch the dodging player, that would change the whole melee vs ranged dynamic and make it more of a skill contest.

Back in early alpha when there was no melee lunge, melee classes were completely useless. You could literally backpedal and shoot to beat them more often than not. As much as I personally hate melee classes for all the grief they give me trying to cap points as a shooty marine, the game doesn't need any more things for people to complain about.
Due to the design of the melee system itself, lunge is necessary. What we need to find is the balance between too much lunge and not enough. I don't think spamming fast attack should be enough for any melee character to catch up to someone sprinting in the other direction for example.

Stupid Iframes

Maybe removing is a little too extreme but it should be reduced fir sure. The problem is not lunging itself, but when you put together lunging, target lock, fast attack spam, the insane melee damage, the poor d-bash and a little lag...
Hell in this game a sword is more dangerous than a bolter...

I'm of two ways about it, on the TT there's something called sweeping advance which basically means two units are in close combat and one wants to run from the other, there's a chance the attacker catches the fleeing unit and kills it.
I wouldn't know how to translate that to the game or if it even has a place.
Melee certainly feels jank as hell right now and I'd like to see stuff like hit detection and netcode fixed before they fiddle with any mechanics.