You may have heard that Nathan Rabin, the writer who coined the term "Manic Pixie Dream Girl" and named the trope apologized last week for doing so. Despite the fact that the piece itself comes across as being disingenuously self-aggrandizing, I actually both agree and disagree with Rabin's apology. While he's right that the term has been wrongfully expanded to encompass characters that only vaguely fit the bill, the term itself is perfectly suited to the purpose for which it was coined: to identify female characters who exist solely for the purpose of helping a male protagonist self-actualize.
Rabin cites Zoe Kazan's (writer and star of the film Ruby Sparks) criticisms of the term as one of the reasons he is apologizing, but I don't agree with her take on the situation either. While she's spot on that writers rely on cultural props to signify personality rather than doing the work to flesh out their female characters, this is the very practice that the manic pixie dream girl trope is meant to critique.
The term itself isn't meant to be shorthand for "quirky and cute." Though I see how it has morphed into that through usage, the term is meant to be an identifier, not an accusation. To me, Ruby Sparks is a movie about exposing the lie of the manic pixie dream girl. The film centers on a protagonist who literally manifests a woman in order to serve his ego, and then gets bent out of shape when she dares to have an inner life of her own. The term "manic pixie dream girl" is a condemnation of the trope as a literary crutch, not the personalities that often get associated with the term.
I actually loved Ruby Sparks. It's a great movie that you should check out if you haven't seen it, but the message that I got from it (which, I guess wasn't want Kazan was trying to convey apparently...?) was that the movie was a direct dissection of the trope. Ruby is initially presented to the audience as a one-dimensional paper-thin character who gradually reveals herself to be a whole lot more, much to the chagrin of her writer boyfriend/creator who only wanted an MPDG to serve his emotional whims. When he realizes that she is beginning to develop a unique personality, he intentionally fucks with her to try to keep her from self actualization because he's afraid (and rightly so, the little shit) that she'll want more or better than him as she allows herself to become a whole person who exists outside his personal desires.
The movie is actually pretty brilliant. But I saw the film as a way to pinpoint the fact that no matter how reductively you to try to frame them, women are more than backgrounds upon which men can work through their personal demons, and to highlight the specific kind of hipster/artist fantasy that leads to the creation of one dimensional female characters of this sort in the first place; essentially, to undermine the MPDG trope. I thought that came through loud and clear. To me, Ruby is a manic pixie dream girl, but the wit of the film comes from demonstrating all the problems that would arise if women really were just the aimless supporting characters in the lives of their men.
At the end of it, I think "manic pixie dream girl" is a useful and instructive term that describes a sexist phenomenon, and excising it from our cultural lexicon is pointless. I do think that we need to be more nuanced about our application of the trope instead of simply using it to signify any character who happens to approach Zooey Deschanel's orbit.