I'd say the message still stands even with how beautiful Kaerikuro/Makoto is. We all obviously know it, and a lot of people in the story do too, but SHE doesn't. She's always been told she's ugly to manipulate her and make her insecure. Takoha was saying that just as much for her as he was to rant at the old hag for putting her down all those years. As he said, she's the same as Souboutei by preying on people's insecurities to manipulate and control them. Kaerikuro definitely needed to hear that.
Although with that last page, it makes me wonder if there was another reason to seal her power than just using her...
Also, she looked so much like Seiichi in the flashback. Always nice to see a noticeable family resemblance in character design!