Creamy Mami is a weird show. Contrary to what's implied by the premise, the show is only about 50% idol-singer stuff. The other 50% is made up of The Random Supernatural Slice-of-Life Adventures of Yuu Morisawa. In the first 26 episodes alone, Yuu meets an alien devil, an evil shaman lady, two ghosts, two princes, a tiny black stag that brings bad luck, a lost angel in a jester outfit, a magical man on a comet who brings dreams to children, an artist who lives with a unicorn in an alternate dimension, and a Zashiki Warashi. You might be wondering what any of these plot-detours have to do with Yuu's singing career; the answer is usually "nothing whatsoever."
And Creamy Mami isn't the only Magic Idol show to take this approach. The Full Moon Wo Sagashite manga spent a lot of time focusing on the shinigami characters, their backstories (only one of which had anything to do with pop stardom), several love triangles, and Mitsuki's backstory with her boyfriend at the orphanage, while Mermaid Melody melded idol-singing with Sailor-Moon-ing and let the fight between good and evil carry the plot, and Lilpri used a similar tactic with its "rescue Fairyland by collecting MacGuffins" plot.
All of which leads me to this conclusion: A Magic Idol Singer's story cannot carry the plot of a multi-episode series on its own; it needs help.
To understand why, compare these idol singer stories to other performing-arts series like Swan or Skip Beat: both Masumi (a ballet dancer) and Kyoko (a tv actor) are artists. Each one is constantly honing her craft, seeking out new teachers and mentors to expand her horizons, entering high-stakes competitions, running herself ragged practicing late into the wee hours, and even traveling to foreign countries in search of a new challenge. These girls bleed for their craft.
By contrast, the idol-singer fantasy is all about not working hard or bleeding; it's about effortlessly soaring to the top of the pop scene in a single bound. When your heroine's singing ability, her dancing ability, and her songs' lyrics/music were all obtained through magic (as in Creamy Mami and Lilpri), then there's nothing for her to practice, nothing to create, no rungs of a ladder to climb. Full Moon Wo Sagashite avoids this better than most — Mitsuki writes her own songs, and often must work within parameters mandated by her agency — but it still resorts to plenty of unrelated shinigami-nanigans. It's hard to wring a multi-episode plot out of a premise that revolves around instant gratification.
Furthermore, you kind of can't show your idol singer heroine practicing or honing her craft that much because from what I've read, idol singers are kind of... supposed to suck. This article notes that "the idol’s lack of sophistication is endearing," like a moe girl tripping and falling on her face is endearing, and this one doesn't mince words when it snarks that "the Japanese industry has always told us that consumers like barely-trained, not-too-good-looking, off-pitch idols." (Sidenote: Inspired by the latter article, I went on Youtube and watched a bunch of Girls Generation vids, followed by a bunch of AKB48 vids, and HOW IS THIS EVEN A COMPETITION!? At the very least because of GG's amazing mile-high gams. And their significantly less stupid outfits. And their superior dancing skills.) And to be fair, we see plenty of that on this side of the Pacific: lousy singing didn't stop Britney Spears, Katy Perry, or Miley Cyrus from making it big.
Anyway, the point is that the Magic Idol's story can be told in the space of a single episode: girl gets magical powers, girl gets discovered, girl instantly becomes famous and successful with minimal effort. The end. Maybe you throw in a jealous female rival, a bishie love interest (or several), a few festivals and competitions, and some spicy scandal, but that's about it. If you don't want to limit yourself to a one-off OVA like Fashion Lala, then you have to pad the story with other things. Hence, bring on the aliens, ghosts, fairies, mermaids, and grim reapers. They may have fuck-all to do with being a pop singer, but at least they'll hold the audience's attention.
And Creamy Mami isn't the only Magic Idol show to take this approach. The Full Moon Wo Sagashite manga spent a lot of time focusing on the shinigami characters, their backstories (only one of which had anything to do with pop stardom), several love triangles, and Mitsuki's backstory with her boyfriend at the orphanage, while Mermaid Melody melded idol-singing with Sailor-Moon-ing and let the fight between good and evil carry the plot, and Lilpri used a similar tactic with its "rescue Fairyland by collecting MacGuffins" plot.
All of which leads me to this conclusion: A Magic Idol Singer's story cannot carry the plot of a multi-episode series on its own; it needs help.
To understand why, compare these idol singer stories to other performing-arts series like Swan or Skip Beat: both Masumi (a ballet dancer) and Kyoko (a tv actor) are artists. Each one is constantly honing her craft, seeking out new teachers and mentors to expand her horizons, entering high-stakes competitions, running herself ragged practicing late into the wee hours, and even traveling to foreign countries in search of a new challenge. These girls bleed for their craft.
By contrast, the idol-singer fantasy is all about not working hard or bleeding; it's about effortlessly soaring to the top of the pop scene in a single bound. When your heroine's singing ability, her dancing ability, and her songs' lyrics/music were all obtained through magic (as in Creamy Mami and Lilpri), then there's nothing for her to practice, nothing to create, no rungs of a ladder to climb. Full Moon Wo Sagashite avoids this better than most — Mitsuki writes her own songs, and often must work within parameters mandated by her agency — but it still resorts to plenty of unrelated shinigami-nanigans. It's hard to wring a multi-episode plot out of a premise that revolves around instant gratification.
Furthermore, you kind of can't show your idol singer heroine practicing or honing her craft that much because from what I've read, idol singers are kind of... supposed to suck. This article notes that "the idol’s lack of sophistication is endearing," like a moe girl tripping and falling on her face is endearing, and this one doesn't mince words when it snarks that "the Japanese industry has always told us that consumers like barely-trained, not-too-good-looking, off-pitch idols." (Sidenote: Inspired by the latter article, I went on Youtube and watched a bunch of Girls Generation vids, followed by a bunch of AKB48 vids, and HOW IS THIS EVEN A COMPETITION!? At the very least because of GG's amazing mile-high gams. And their significantly less stupid outfits. And their superior dancing skills.) And to be fair, we see plenty of that on this side of the Pacific: lousy singing didn't stop Britney Spears, Katy Perry, or Miley Cyrus from making it big.
Anyway, the point is that the Magic Idol's story can be told in the space of a single episode: girl gets magical powers, girl gets discovered, girl instantly becomes famous and successful with minimal effort. The end. Maybe you throw in a jealous female rival, a bishie love interest (or several), a few festivals and competitions, and some spicy scandal, but that's about it. If you don't want to limit yourself to a one-off OVA like Fashion Lala, then you have to pad the story with other things. Hence, bring on the aliens, ghosts, fairies, mermaids, and grim reapers. They may have fuck-all to do with being a pop singer, but at least they'll hold the audience's attention.