Just, no.

The Combo itself works just fine, and if you're not using it because you're scared, then you need to practice more.

Take Ifrit for example. When he hunches over to cast eruptions under someone, or when he activates plumes, this is the perfect chance to run behind him and nail him with Riot Blade. Even then, you can get behind him and whack him with it regardless of what move he's doing, as long as it isn't the knockback.

This is also EXCEEDINGLY easy on Miser's Mistress considering she's very easy to stun and she only turns to WS/Breath.

We already have frontal activating combos and one that doesn't even require technical positioning. A rear combo WS isn't unreasonable.