Her self-sabotageing habits are more than just some hindrance or way to stop her from being a major league threat. She's quite capable of being a dangerous enemy even with it, and when she messes up she leaves quite a lot of collateral damage in her wake. On both her side, and the one she's fighting.
I touched on it when I talked about why I personally despise her so much, but her self-sabotaging nature and refusal to acknowledge her own faults is something special, as much as she would hate it being said like this, it's real, it's human. It's something that people do in real life, something that everyone has seen or done themselves. It makes her more than just some generic ball of hate, it makes her a person, a horrible person, but a person nevertheless.
It's what makes her more than just some villain, because you can be a good villain without being a good character. She's a good and well written character, like almost all of the ones from Gargoyles, just one you're intended to hate. Take it away and you just have some grudge filled pile of spite and hatred, nothing about her would be compelling, nothing about her would be interesting, she would lose that spark that makes her who she is, and what makes her so easy and enjoyable to hate.
Without that hatred I wouldn't have reacted so vehemently, I wouldn't have been as invested in the entirety of the 12th night, and it all stems from her being self-sabotaging. Nothing she would have done would have elected as much of an emotional response, because there'd be no human connection. She'd just be some generic bad guy who wants to do bad things because she is bad. With it, she's a multifaceted character with clearly defined flaws and a reason why no one can get through to her, because acknowledging that she's in the wrong is to acknowledge that she has always been doing the wrong thing, that everything she sacrificed and went through was for nothing, and no matter how much it costs her and how much it hurts she can't do that.
I'm not saying it can't happen, but what I'm saying is as a quest, as a story, it shouldn't happen.