In the post below about Manic Pixie Dream Girls being born, appropriately, during the manic phase of the 15-year excitement cycle, there's only one off-hand mention of the type from pop music during the restless warm-up phase of the early '90s (the phase when this type shows up).
It's worth fleshing that out with more examples, though, because at the time and ever since, the focus has been on the hard-edged aggressive women of the early '90s heyday of alternative rock, rather than the traditionally feminine helpers and partners of men. There's also the focus on the irony trend, when there was a notable counter-trend of heart-on-their-sleeve sincerity.
The background for this phenomenon was the vulnerable refractory phase of the late '80s, when soft rock and emo power ballads were the norm, and when there was a widespread fixation on being victimized (most obviously in the "Save the children" movement). During the warm-up phase of the early '90s, people were out of their refractory state, and women had to let men know that, hey, it's OK now, you can come out of your shell and we won't require a schmaltzy prostrating power ballad in order to trust you. We can just mix it up with each other again, and we women are only too eager to nurse you out of your funk if necessary -- how else are we going to connect?
That is the broad role of the Manic Pixie Dream Girl, and in pop music it's a more impressionistic persona that the performers convey, rather than a clearly defined character who plays such a role over the course of a narrative movie. But the basic traits are still all there -- quirky, eccentric, adorkable, directly addressing her male love interest, who may have trouble leaving his emo funk behind, but using her feminine charms and allure to pick up his spirits and get them together as a couple.
Other than that, they come in various flavors. However, all of the female singers below were born in the manic phase of the late '60s, and imprinted on that mood at an early age (as well as imprinting on the next manic phase, the early '80s, when they were 15 and just getting out of puberty). As with the actresses born in the late '60s, these musicians were best suited to playing the role of leading the charge out of the emo phase (the polar opposite of the one they've imprinted on and find most natural).
Many of the other alterna stars were born in the late '60s as well, but I'm leaving aside the hard-edged in-your-face ones (Liz Phair, PJ Harvey, Veruca Salt, etc.). This is only looking at traditionally feminine ones who want to help weary guys come out of their late '80s emo cocoons.
Hope Sandoval is not as manic as the others, but no less of a pixie (5'0, size 0). As a waif, seemingly abandoned by her caretakers, she projects an anxious attachment style, but that insecurity does not diminish her eagerness and sincerity to form a deep connection. The anxiety only emphasizes how much she wants a partner, which combined with her petite frame and pouty lips, make her seem like a child who's upset that the immature boys aren't paying attention to her on the playground yet, but she's going to keep on trying until they do.
Guys in a social-emotional refractory state are behaving like prepubescent boys in a way -- "keep those annoying girls away, we don't want to play with them." But men in such a state are doubly wary of leaving their shell because they anticipate the women being in the same "leave me alone" state -- so it falls to the women to send the first signal that the anti-social withdrawn mood is over.
"Blue Flower" and "Fade Into You" (1990, 1993; live '94)
Juliana Hatfield Three
Another waif with an even more childlike voice -- this serves the purpose of not setting off the guy's alarm system. She couldn't be any less threatening -- "Don't worry, I won't bite". Guys coming out of a refractory state need to be approached more gently, so it's not a job for the hard-edged aggressive type of woman. It has to be a disarming pixie.
"Spin the Bottle" (1993)
This case is approaching a hybrid of the disarming feminine nurturer and the in-your-face badass chick type of the same era. But she stays just enough on the nurturing side of the line, without it being primarily an aggressive come-on. Pretty sensual though, especially in a live performance -- I never expected her to have such a ripe body, based on the "Human Behavior" video that introduced her to the world.
"Come to Me" (1993; live '94)
Not the purest example of the type -- more of a neurotic overly attached girlfriend, rather than one coaxing you out of your shell to begin with. But that's still the opposite of being refractory and not wanting attachment whatsoever. Plus her image was an eccentric waif, and the video was in constant rotation on MTV. So it's still worth including in this survey.
"Stay (I Missed You)" (1994)
Just look at how unaffectedly smiley the lead singer is, and remember this is an all-girl early '90s punk-inspired band. Hence the label "cuddlecore". Her warm welcoming vibes are too infectious to resist -- you couldn't possibly want to languish in your goth/emo cocoon any longer, could you, anon?
"New York City" (1994/5?)