It's not so much villainous clichés (though that's definitely a part of it), but all the Ascians we've met so far are overwhelmingly arrogant. Even Elidibus, in his own way.

Igeyorhm simply felt like we weren't worth the time or effort to actually kill. It's not until we regain our blessing and are so powerful within it that they realize letting us live was probably not a very prudent decision.