You are right, it is not complex. It is clunky. It was relatively fine before the November patch if we disregard the Radiant Fire works. But it lost every bit of flow then, and now it became slightly worse.
I guess one could argue for raising the skill-ceiling if a build has exceptional output even when playing less-than-optimal (which I would not say FB had) but they usually end up raising the skill-floor and they do it in such a weird and counter-intuitive way that you just feel uncomfortable playing the profession afterwards. But I guess it accomplishes the goal of "let's pull back the numbers on that build."
Also, this hurts support more than damage dealers. It is one thing to integrate preparation or a long CD into a DPS rotation, (still not a welcome addition, though,) but as support you want your skills to be ready-to-go to handle whatever situation that arises. But in both cases your character should be a tool that you use to overcome a challenge - it should not be part of the challenge itself. To put it into raiding: every glance I throw on my toolbar or my boons/conditions is something that takes me further away from the encounter and closer to fighting a bot, reducing the impact of whatever effort devs put into designing that encounter. But I digressed a bit far. In essence: brain-dead, off-the-cd mantras might have been boring, simple, but having simple skills serves the content by making the player able to focus on the world instead of their character.