it wont kill melee classes if:
1) ranged white attacks only apply for certain classes: Mage, Priest (maybe?), Druid, Warlock(don't know about this one). These classes don't have white hit based skills so a ranged white attack would not break the melee pvp system. Don't base it on weapon, base it on class. This also wont make w/m a ranged class, no matter what weapon they are using.
2) Range of white attacks on everyone else based on weapon size- Not saying a rogue would get 2 m attack and 2handed axe would get 15 m. A small adjustment, like 2m for dagger, 3-4 for sword 1h axe, 5-7m for 2handed weapons. a SMALL adjustment. This again wont kill melee classes. Just means rogues have to close more of a distance than a 2handed axe user.
There PVP, and white attack dependent classes don't get OP... Easy fix.
As for my suggestion, range for skills that are melee should be based on the weapons attack range. Therefore if you aren't in range for your white hits.. your other skills don't hit. So instead of arguing an increase in white hit range for those classes, I am saying a REDUCTION in normal skills based on weapon. Therefore, if you aren't hitting with Lightning weapon, you know to move closer. Instead of hitting the "non-sweet spot" where your Lightning touch hits, but your white hits don't. Should be based on weapon range (course I don't know how well this will work with RW programming skills). Might just be better to boost a small amount for white hit range to be about the same or a little better than skill range for all weapons.