I don't mind the DW Shaman when it comes to PvE, I kinda like the berzerker-type with an axe in each hand. What I would love to see is a talent in the level 100 tier which allows Enhancers to spec for 2H for a playstyle more suited for PvP (EF and SET are shit awful anyways). I find the Enh Shaman sorta boring these days in PvP, and would love to see the spec with a more hard-hitting build similar to the Vanilla Shaman.
Though I don't know the current state of DKs, I like to compare it to DW vs. 2H Frost. A DW Shaman could be optimal for steady DPS in a PvE environment where uptime is more managable, while a 2H Shaman has more immediate burst with fewer attacks in the more unpredictable PvP environment.
This coming from one of the main theorycrafters for Monks; that and I've had little to no experience with shamans, here is my take
Really the fact the monks are able to dual weld as well as use 2-handers is partly the mystique of the class. If you look at Shao Lon (I think that is right) Monks, in their dance routines, they do use pole arms and swords. As well as other weapons, some look like axes, or what-not. So you have references to real life that the devs used.
As for differences between the two, after the recent change to Way of the Monk (and a hidden buff to Tiger Strike's proc rate for Dual Welding), the damage difference between the two is nearly identical. It's to the point that whichever has the better stats is the one to go with. But to the point that someone made about it being hard to balance the two for Enh Shamans back in the day, I can say for certain that Monk damage calculations are quite complex. Since there is a dual welding co-efficient that lowers the damage while dual welding. Damage co-efficient that are hard-coded into tooltips, and then factoring in AP -> damage within the tooltip. No other melee class has this type of calculation.
I actually played the closed beta back in the day and my first char live after release was a Warrior, but being the noob i am i put all my talent points into protection talents (yey 10% less damage taken for 5 talent points, no one will kill me muhahaha) which made leveling EXTREMLY slow and boring so i quit around level 21-24.
As i am a Developer myself and have to deal with ~15 years old code sometimes, i can tell that some tasks are just to time-consuming if you want to change them without crashing anything (like in WoW's case with the standard 16slot Backpack) to be worth it.
So considering that the Shaman Class is as old as WoW there might be cases like that in there somewhere, too.
Especially considering what Hinalover said about way of the monk:
DK's are a newer class as well and every spec could dual-wield from the very begining, i would think they might have something similar as the monks, and Shamans would need that too.
Not saying it is impossible, but it is not as simple as some think it is (myself included before knowing how it works with monks).
So that could very well be a reason for them to push it off the table, if someone at blizz already had such an idea.
Why do people always disagree with implementations? It's not going to drastically change the game or the class, just add another option for shaman.... yet so many people eager to combat it. Miffy has been correct in all his stand points so have many others but people just keep saying NO... cause reasons.... Alot of us want 2H because we prefer that playstyle of bigger hits as opposed to faster swings... that is all