I have personally done every role over the years on raids at different phases of my gaming life. So read this with that in mind, I understand the basic game mechanics when it comes to moving and casting. This being said I think most people who do these "fancy maneuvers" tend to be doing them while playing melee classes where getting in place when moving from one target to the next and finding optimal placement for melee is a key factor. I think it should be noted as someone with severe ADHD I am constantly moving and fidgeting on classes it's possible to do so on. Moving while fighting on classes such as Bard or Monk does not negatively impact DPS from what I have seen as long as you don't get out of effective combat range.