When this cropped up in Naxx - as the result of FT doing the same amount of individual strike damage regardless of weapon speed; heavily favouring fast daggers for more hits and Caster Weapon Spell Power to boost the output - the developers intervened around 3.1 to change the way FT would work so that the per hit damage would scale with the Speed of the weapon. Thus, the total FT damage put out by a fast weapon would be approximately equal to the total FT damage put out by a slow weapon over the course of a fight. Once they did that, you ran into a wall where the issue wasn't that using a fast dagger would cost you FT damage - slow/fast was now ballpark - but instead that you lost Lava Lash damage because of the lower strike damage (that nifty "X->X*2 Damage" stat on your weapon), of the fast weapon that would no longer be compensated for by higher FT damage output that used to occur from more strikes. Therefore, a fast weapon in the OH was now a net DPS loss. Itemization chaos ensued as choices which were viable suddenly vanished into the ether; leaving a 25 Man Interested Enhancement Shaman chasing exactly one drop for the OH slot heading into Ulduar: Angry Dread.
Pity the Enhancer who found himself in line with others.
Meanwhile, fast off hand weapons were now, for all intents and purposes, exclusively Rogue domain and quickly built up the shard pile as Enhancement would be living with +-2.6 speed weapons in both slots from this day forward; especially fun when Wrath Fist Weapons were hand specific and you'd need to wait for a One Hand Axe or Mace to drop to fill the opposing slot.
Ulduar, having been itemized just in time to see the change made, wasn't much better. Sure, a blessed Enhancer could get the fist off Hard Mode Flame Leviathan if they were in a quality guild.... and there were no Rogues in front of them. But, most had to work their way into Thorim for his maces to fill the OH or Mimiron for an alternative in the MH on 25 Man.
Pity the 10 Man Shaman who had to down Hard Mode Iron Council or Yogg-Saron to fill their slots.
Things came to a head in Trial of the Crusader when every single available Enhancement weapon drop was on some mode of Anub'arak, leaving the spec gimped until their guild was able to challenge the final boss of the Tier on each setting with regularity. Just before this point, the Devs acknowledged there was an issue as Ghostcrawler would come down from the mount to announce that they would address the source of this readily apparent itemization conundrum:
"Enhancement Shaman.... I have heard your cries!!! This is an obvious problem caused by the reality that Death Knights can't use Fist Weapons, Rogues can't use Axes and you can't use Swords... we shall address this!!!!and, lo, he would return to the mountain top and all would be good.... for a while.
From this day forth, Rogues shall use Axes.... and all shall be good!!!*
ICC would come and the Raid and Dungeons would prove to be a boon of options for Enhancement Shaman: even their own drop. Cataclysm would come, Death Knights would move to STR Weapons and Combat Rogues would become our only shared partner worthy of consideration**. An incredible technological breakthrough in design would allow for the creation of One Hand Fist Weapons for levelling. There would be craftable weapons to take in to your first raid perfectly itemized (although, initially bugged for mats; arguably favourably if you hated farming orbs). Normal modes of the raids would have 2 BoE drops that were usable though Heroic Mode would be complicated by our only other weapon loot being on Nefarian. For the most part it seemed like they had things right... and then folks lurking around the 4.2 PTR started linking the Blacksmithing patterns available from the new dailies and....
Come on guys, you were doing so well!
On a bit more serious note, this is pretty clearly intended to be catch-up gear for those behind on progression and perhaps those (many... so very many...), who aren't farming Heroic Nef with regularity. I know new Direbrew Mugs will be coming to the AH but it seems silly make us wait until September while also providing a bridge craftable for every spec but ours. Especially now that all the Specializations have been stripped from Combat and you opened up weapon options specifically so that you'd have flexibility to allow you to serve more specs/classes. This is why I said elsewhere a long time ago that the WoW Team desperately needs an Editor in the itemization department to keep baseline items with class/spec usability this narrow from getting live - even to the PTR - because it's these moments that drive the idea that no one's giving much thought to the big picture.
*err... based on true events....
** Yes, yes... Hunters. I love my Hunter friends and all but, let's be honest here, they just want their sexy stats. As long as those add up to pretty numbers, the form they arrive in is largely irrelevant to the discussion at hand when they almost never swing them in PvE.