Breh I legit gave homegirl props. She's crazy talented which is why I have high expectations for her musically. It could almost be unfair and unrealistic expectations. It could also be the reason why someone like an Andre 3000 hasn't put out a solo joint. When you are versatile sometimes it can end up a big fukking mess with no direction and that's what I get from Janelle.
I think you're seeing it exactly the wrong way. Her first release was a concept EP... nobody does those. That means it was planned from beginning to end to reflect thematic continuity. So was the first album. There's not only a great deal of continuity in her music in terms of her backing band, the lyrics, the structure of the releases, but also in overall vision. The problem with pop music today (and she is a pop artist, just like Prince and MJ are pop artists) is that it's become so homogenous (and this is actually a scientific fact, thanks to that massive study on the topic) that people can't handle real diversity, the way it used to be done on the albums of artists like the aforementioned. The ArchAndroid, especially, draws from all over the place in exactly the same way as great albums from the past. If you listen from start to finish a few times it'll make sense.
Honestly, to me, some of the stuff you've posted in this thread, like Christian Scott, is much more derivative and lacking in identity than her work (which is not to say it's bad.)
As for London Calling, that whole album has each song in a different genre- from reggae, to rockabilly, to folk, to more traditional punk. If you can get down with that album, and understand why it's considered a classic from front to back, there's no reason to not be able to see the same quality of unity in diversity in Janelle's releases.