I would never think she's underpaid in the past 10 years. Maybe it's so in her early years like late 80s or early 90s. But if you can get the chance to work with one of the best orchestras in the world (Israel Phil, Warsaw Phil, etc.), then why you would be underpaid become a mystery for me. In fact she's currently one of the musical gods/goddesses in Japan with a large cult following. You can see that from the fact that most of her works have been on CD.
Yoko Kanno is an extremely talented composer. Take "Triad" from Turn A Gundam OST2 as an example. What a f**kingly beautiful and haunting piece of music. Her melodic and harmonic capabilities are strong, and despite the fact that she's not academically trained, her arranging/orchestration skills are also spetacular, and she knows how to make good, authentic (well, sort of) world music. The only thing that didn't grab my attention is her eletronic sounds.
Yet one of her tendencies is to listen to music all day. Maybe that's the reason some passages did sound like others' work, and there may as well be direct copies.

I myself came up with a small list of her work referencing others too. I've been picking up passages that sounding like Elliot Goldenthal (mainly from Titus), Sergei Prokofiev (namely, the Scythian Suite), Maurice Ravel (Bolero, Daphnis et Chloe, etc.). In fact there are other influences in her orchestral work that I may not recognize too. Actually that's the reason why I'm mainly attracted to her orchestral music. I can hear bits of all my favorite symphonic artists, yet the pieces itself are still Kanno's.
As for those 'direct copies', I would think of the reason that these are some of her favorite composers, but as of now, I would say to Yoko... you just don't have to do that.
Jam it back in, in the dark.