SimC damage per execute time already includes Inner Demon (PPM based by the way), Chaotic Onslaugh, Crit, and every other parameter that might affect your DPS. Yes, if you could somehow guarantee that every single one of your Chaos Strikes would proc Chaotic Onslaught and Crit, you would be far better off pressing Chaos Strike (let alone Annihilation) over Throw Glaive every single time.
But that practically never happens.
What you are doing here is similar to arguing that in the following graph, your DPS is not 877k (the mean) but the theoretical maximum of 1.17M DPS.
Yes, it is called having a CD. If Fel Rush had infinite charges, you'd bet you ass we would be spamming it all game long over lower DPET abilities.