Yesterday I talked about a great game that you might enjoy if you enjoy that sort of think (my apologies to President Lincoln for the butchering). I also talked about the interruptions of raiding, in particular, about how many boss abilities break the flow of abilities. At first glance this may seem inevitable, that if the encounter is going to be dynamic we must be interrupted. I disagree, with that vague strawman that I just created.
Sticking with the boss AoE, how can we deal with this without running away? Well obviously there is the "make the healer's deal with it" approach. I'm not a fan of that one. Let's backtrack: why are we running away? To avoid the damage. We can do that other ways, and in dynamic, reactive ways, which do not break the flow of play.
Anti-magic shell is one approach: have the DK drop it in time and it will negate enough damage to make running out pointless. This has the downside of placing the burden on one class, though it does add some coordination skill opportunities.
Let's imagine remaking the boss special so that rather than an AoE, it is a single-target, instant-kill, on a random play. Everyone is going to run out still, especially the tanks! Or, we could drop grounding totem. Now players can keep playing but the shamans will be reacting.
Fights could include some sort of added player ability, such as temporary immunity to a spell tree. Incoming AoE? Trigger the ability, but don't go running around and breaking your flow.
With these suggestions, players will still be reacting to the fight, paying attention, but without running all over like headless chickens.
Even with movement, it can have better or worse implementation. Grobbulus was a fight which I did not much enjoy. The constant movement was a physical problem, of actually pressing the right buttons while maintaining movement. It wasn't that it broke flow so much as it never allowed it in the first place. In contrast, I enjoyed being a slime kite on Rotface, where while I was moving and therefore my abilities were limited, it all fit together into a coherent set of actions, much like my vague example the other day where I enjoyed picking up streams of adds; in this case I am using fewer abilities in favor of more movement.
I don't mean to suggest that movement itself is bad. As I just said, it can be enjoyable, but it seems that devs often take "dynamic fight" to mean "players run around a lot" rather than "there are events for players to react to", with reactions including more than just standing somewhere else.