Why I think Shadowbringers Dark Knight is not going to be fun...

[TouchandFeel]

snip

If you watch the GNB part of that video that follows the DRK, it also looks "slow and boring" if you look past the flashy new animations.
If you pay attention to what actions the player is using in the video for any of the jobs, they are obviously not playing optimally and to any of the jobs' fullest capabilities. Since the point of the video was to show off new job actions, it is likely they intentionally simplified how they were playing to make each action used easier to see.
I would not take that video as a proper representation of how any of the jobs shown will actually play.