Look, I use 2h/bow in both PvE and PvP and I feel the pain of sacrificing a monster 2pc bonus for 2 5pc set bonuses. But, stop asking for this; it's a bad idea. A 2h weapon is A SINGLE WEAPON. Not two items. If they give you this then they are going to nerf those weapon lines; or they are going to make 2 DW weapons count as a single set item, ala the dk stone fist "buff" where they nerfed petrify down to 8m.
If one of these weapon lines is underperforming in some area then it should be addressed specifically with ability buffs.