Perhaps there could be different tradeskill loot in each of the locations. Other than Tailoring and Blacksmithing I'm not sure what else would be beneficial. Perhaps Brewing and Jewelery(yet another bump for folks to have enchanters!). Since on THF it is important to work on tradeskills in order to craft the Icewell gear and even the PoFire gear I think it would stand to reason it could be utilized further! Give people additional reasons to have that skill over 200! BTW, lets make everything crafted out of the LDoN's asside for maybe a few items tradeable/attunable to help encourage an economy even further.
Ok, here's an outline of what I'd be happy to see in LDoN's. Just an example using the 1st one on the list.
Rujarkian HillsFocusing on JewelcraftingGems with no merchant value
Precious Metal with no merchant value
Gem Cutter
With just these three types of items there could be several recipes. From doing some research into Jewelcrafting on EQTraders I see recipes that require metals both enchanted and non-enchanted. I also see recipes with gems both polished and non-polished. Enchanting is simple, find an enchanter and they can do it for you.. or make your own

As far as the polishing step. The skill for this step could be around 80-100 or so perhaps? This would help you raise your skill while not wasting other materials. Final combines could range in skill level with combines using both enchanted and polished materials being the hardest to do yet giving you the best rewards. Just like the other zones that drop tradeskill loot there could be large amounts of the items to combine just for skillups. They could be just something you would sell to a vendor for a little bit of plat or perhaps be made No-Drop and could be turned in for a quest, the result of the quest would reward you with an item you could sell to the LDoN merchant for some points.
As far as the other three areas are concerned,
Takish-Hiz = Tailoring
Miragul's Menagerie = Blacksmithing
Mistmoore Catacombs = Brewing and or Poisoncrafting
I think that Hard LDoN's could have their own unique items available for crafting following the same outline as the easy mode ones but excluding the practice combine drops from the loot table. If you're able to do hard mode then you should already have leveled up your tradeskills to a point where you don't really need much more practicing
I don't think people need to be able to craft an entire set of armor from the LDoN's but a few nice items for each type of armor would be nice. Also with the jewelcrafting I think the results should be on par with some of the items you could get with your points. The very best item being similar to that earring you can get with 2450 points BUT materials being really rare so that it's not something that'd be easy to just farm through tradeskills.
Zalux