Because they will give you new grind spots with new DLC... don't you understand greed is big...
They DON'T give you new grind spots though, and that's a huge problem. I HATE the Imperial CIty, but I love Wrothgar... so where do you think I spend all my time? The Imperial City, of course! IC has 2-3 times as much XP per mob, plus you acquire VR16 mats so much quicker by farming Tel Var stones.
@ZOS why don't you want players to spend time in beautiful Wrothgar? Boost mob XP to the same levels as IC, and so many complaints about PvP will go away!
There are still PLENTY of good grinding spots. You just have to put in a little work to find one that hasn't been widely publicized. Sure, they nerf the ones that people flock to. Just find another one. Smart people aren't going to post the location of their spots all over the internet and ruin them. It's really not hard to find a good grinding spot.