It is slightly unfriendly to casters. It is not nearly as bad as you say if you know the order of the fight, which you should after 3 hours.

Here is a 10 second picture to show you how little movement there is in this fight if you do it right.

Start by going to 1 before you cast. When the first zone pops, step twice to 2. Then step to 3 (back to 1) and wait for middle void again. Then, 5 steps to center. After knockback, back to 1.

That's it. There is very little movement at all. People go crazy trying to get way over to the left and way back to the center each time - the majority of movements are 2 steps.