Dancer might have less buttons, but it forces you to watch the skill bar more than other jobs do.
I can play tanks and some DPS jobs (Samurai for example) without UI, and it works just fine. That's unthinkable with the reactive gameplay of the DNC.
That also means you have to multitask more compared to "autopilot jobs", who can focus on mechanics while leaving their rotations to their muscle memory.

Just saying this, because people always talk down on the Dancer, even though it's exactly as demanding as, say, a NIN, but for different reasons.