im not much aware of their philosophy and decisions , but srsly what is their reason not to let us play 2 hander? while thrall himself plays 2h with that weapon (i remember wod cinematics thrall using 2 handed like marad as a paladin did was so cool )
if they make different weapon enhancements ,frost ,fire,wind,lightning,and earth elements , each having good mechanisms attached to them ,baseline , and provide unique playstyle , then tune them to have double ,or even tripple effects on 2 hander (cause you have one enhancement instead of 2 in dual wielding) and also let lava lash be an off-hand AND 2 hand ability , there would be no restriction for players not to use 2 handers just because their design makes it not valuable .