I don't get it, who has 4000 triumph?
Well stuff. The main reason people want portals is to get to AH methinks. So what if they just added AH to Dallranan? People would never leave Delorean. Why is there even a city in Northrend? Why? It's a loving war zone. This is bullstuff.
Also mounts can fly in loving space but if you want to fly in a (SOMETIMES) cold place you have to pay FIVE THOUSAND GOLD. DAMN.
This is happening once Cataclysm is released... All the new content is going to be on the Eastern Kingdoms, Kalimdor, and the Maelstrom. There will be no new sanctuary city. There will be no reason to be in Dalaran/Shattrath unless you are leveling through Northrend/Outland. Where the portals are now they are putting class trainers, and they are also adding auction houses as well. They want to make it so the old major capitals get filled and used.
Also, the conversion rates aren't equal. 1455 emblems of either triumph or frost or both equals to 4000 justice points (and there are people that definitely have that or more saved up that they haven't used). The hard cap, later on, will prevent people from saving up all their points in order to get all the good gear after a season end (similar to how arena points and honor points currently work). The value of each item purchased now will also be changed to match the new currency. So, I assume, something that costs 35 frost emblems will cost like 96 justice points.