Dustwallow Marsh got a revamp during Vanilla WoW. Because of this it had a very low priority among the devs when it came to changing the zones for cata. This is why Dustwallow Marsh's quests remain essentially the same despite the massive changes that has happened around the zone.

Although there is a highway in Dustwallow leading to the Barrens I haven't seen any quests yet that even acknowledge the Theramore highway or their role in the Barrens. All I see are just a few Ogres Hordeside trying to take back their village from a dragon (Onyxia) that died years ago.

I hope they have a facelift coming. It seems totally clueless of Blizzard to ignore the effect of the war on Jaina's lands and clueless for them to invoke "just got a facelift in Vanilla" to ignore the real problem.

Thrall is no longer a factor in the Horde and Jaina no longer has access to appeal to the leader of the Alliance. Now her Alliance and the Horde are at war.

What does she think of Garrosh's actions? Sylvanas' actions?
What does she think of the war in South Barrens?
How does she want to involve herself in the war? A necessary war? Or seeking to find peace?

I was extremely when my Worgen rogue battled himself from Darkshore to South Barrens and seeing the war and the effects of the land and then getting to Theramore...

"What the @#$% do you mean I have to go get Thresher Oil again?"

Actually, Mudsprocket was during Burning Crusade, but otherwise you seem to be right. Which is frustrating, because it leaves a gaping hole in the Alliance's storyline for Cataclysm, second in import only to the Worgen just being dumped in Darnassus with no plot in sight until Eastern Plaguelands, while the Undead get to see what happens after Gilneas.

It may just be that those storylines were part of lower-priority zones, but it leaves Cata's "Old World Revamp" very one-sided in terms of content. I don't mourn the loss of Southshore (Except for going sight-seeing in Lordaeron) but the Alliance side of things is nowhere near as cohesive as the Horde side.

Speaking of priorities, what the hell happened to Arathi Highlands? That hadn't been touched since Vanilla, why'd it get skipped?

They wanted to release Cata in 2010, therefore, they had to stop the zone rework and make sure the game could be played. They admit that Arathi, Silithus, and Duskwallow Marsh are the least touched for these reasons.

The highway IS mentioned in the south barrens stuff, Alliance Side, as the tie in to the archaic and outdated Dustwallow content. "We built a highway for supplies and are getting nothing, go see what's going on!"