These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
And there are fans who just don't think she's as interesting as Chocolat.
Designated Hero: Though the protagonists are certainly not as villainous as the Ogres, their habit of harvesting human emotions for energy sounds like an evil plot straight out of Sailor Moon, though it doesn't seem to harm them.
Evil Is Sexy: Well, sexier anyway. After becoming the Ogre Princess, Vanilla sports an elegant evening gown when transformed into witch mode.
Growing the Beard: A little less than halfway through the series, when it stops being "how to get boys to like you" and becomes a more straightforward magical adventure.
Values Dissonance: A lot of fans in the west (where tomboyish girls are seen as more desirable) don't see anything wrong with Chocolat's behavior early in the manga, and think she's treated way too harshly. This may be the reason why it never really took off outside Japan.
A chapter in the manga had the Accidental Aesop that "crying a lot will make boys like you!"
These overlap with Family-Unfriendly Aesop, since there's some truth to the idea that boys prefer cute, submissive, vulnerable girls like Vanilla over brash, strong-willed, outspoken girls like Chocolat, epecially in Japan.
The Woobie: Both Chocolat and Vanilla can be this.