As many others have mentioned, the xp is terrible in Amrath. The ransack changes have done nothing to help the situation and have actually made it less desirable to run Amrath for xp if you are patient. You just hold 18 and run lower quests which are magnitudes better xp/min.
Poor xp is just the main reason these quests are run less. Sometimes quests with poor xp get run if they have other desirable qualities like loot, flagging requirement, fun factor or challenge. The loot is mostly obsoleted so that has contributed to the decline as well. Why flag for a raid you have no reason to run. Very few people would describe Amrath as "fun" though I'm sure a few enjoy it for that purpose. While it is challenging, those running it for challenge are probably either solo or in channel and guild groups.
Again, Turbine wonky logic rears it's head. Why is there such a massive hesitation to bump the xp to reasonable levels here? It's a simple fact that once players hit epic levels they can run pretty much any epic quest and get more xp. That's a Turbine created design hole right there. The fact that any epic quest gives 3x or more xp/min on average than a comparable heroic quest is a major design issue and Amrath and IQ are the reasons why. How come I don't get the 3x xp bump when I run Amrath on hard or elite? They are level 20 and 21. It should be treated as epic for xp purposes at that point. I think I'm through trying to understand the logic here. People have been saying for years that the xp in Amrath is low and there has been deafening silence from Turbine about it. They either have no answer or one so illogical, we'd laugh at them if they told us.