Okay, so there is no denying Asami’s flawless badassery. Look at her taking down those Equalist chi-blockers with nary a hair out of place, right out of the gate, where it took Korra and company episodes to learn to fight them effectively.
But it’s probably because she trained alongside them. Not knowingly, of course—whatever else he did, Hiroshi gave her enough space that she could live her own life. Still, it’s no secret that he was not only the Equalists’ number one provider but that he fully intended Asami to join him.
Asami spent her life unwittingly surrounded by Equalists. With a workaholic father and, from what we see, a cloistered life, she had only her father’s company workers and clients to turn to. Her only form of escapism was her love of pro-bending, and for reasons she could never understand that only drove the few friends she’d made away from her. (I imagine her being overjoyed when some of them agreed to go see the finals with her, only to wake up abandoned and confused after the assault had ended.) Getting to date one of her favorite celebrities was not only the brightest point in her life, but gained her friends that were there for her, regardless of her own choices and her father’s. Of course she’d fight for them, for the morals her mother had instilled in her (that she always thought her father believed in as well. But later she realizes he was only too busy with his glorious revolution to tell her otherwise).
But she’s probably grateful for the masks. Because beneath every Equalist mask is likely a Sato employee, a client, the face of someone Asami has spent her whole life knowing, and she has no choice but to take them down before they hurt the only people who have ever stood by her.
And that’s just one more reason for her to resent her father.