I'm comparing them to the single target version of the same skills, which admitedly isn't the best comparison since you would be trading it for the first two actions as you mention, not it's single target version. Other than the potency values... I'm not saying anything different than you with regards to not using AoE skills on a single target?

While true that against exactly 2 mobs it is worth using the AoE flourish procs, I find that I am usually inclined to not use flourish in such a situation at all because most of the time it's nearing the end of a pull where.only a couple mobs are left and I'd rather save the CD for the next fight to get more bang for it's buck.