I can only give examples from WoW as it is the only other MMO I've played to any real extent. I will give a basic explanation of the rotations' foundations, but they end up getting more and more complex at higher levels - just like in this game.
DoT management class. You have DoTs with short and staggered durations so that they don't always align in their reapplication. As the DoTs tick you have a chance to gain a resource point (capped at 5). You have a short duration DoT that costs a resource to apply. You have an ability that costs a resource that deals damage based on the number of DoTs you have active on the target.
Proc class. You have a basic cast spell. You have an instant spell that is guaranteed to crit. You have a big attack with a long cast time. Whenever you crit 2 times in a row with any spell, your next big attack is instant. Your dps cooldown causes all of your attacks to crit for a few seconds.
Rng class. You have a meter that builds over time. You spend meter on an attack that generates a resource point (capped at 5). This attack has a chance to hit twice and give another point. You spend 5 points to maintain an attack speed buff, or on a big attack. You have an ability that gives you a random buff for a while - one increases meter generation, one increases the chance that the builder attack hits twice, one that makes the builder attack generate 2 points per hit, one that makes the point spender attack also extend the duration of the attack speed buff, (other ones I don't remember). The random buff ability might give one, two, or five of these buffs.
It's true that rng plays a part in each one of these mechanics, and that they typically have builder-spenders. However, these mechanics are notably underdeveloped in the rotations in FF14 and I think incoporating them in addition to the good, and well-developed sequence mechanic that 14 uses at length would go a long way to making an even more diverse landscape of job rotations. Many of the jobs in FF14 have the foundation already, the devs have just been expanding in them in the wrong areas. The most interesting part of red mage's rotation is their balance of black and white mana, but for some reason this expansion they just tacked on another ability at the end of their scorch sequence.