So I was listening to Sequentia's "Shining Light" recording the other day. It's 12th and 13th century Aquitanian chant music. And the second track, Verbum patris humanatur, o o, just reached out and slapped me. First, if a song's got an "o o" or an "eya" in it, it's usually pretty joyful and fun, and this song has both. But the other thing, the thing that made this song seem so much more singable and accessible than anything else in the recording, was the syllabic setting. Most of the syllables took one note.
I need to look into this a bit more, but my vague understanding is that this is typical of world folk music. Early chant also follows this model, if I recall correctly. [citation needed but I'm pretty sure it's in Hoppin.]
Art music, on the other hand, is a more conscious use of musical tools to achieve some artistic effect. My growing suspicion is that the long melismas in chant are more art music than folk music. It's probably no accident that their elaboration and eventual polyphonic settings rise with the rise of better musical notation (an important marker for art music).
So, depending on context, I should possibly be not looking to highly melismatic chant pieces for melodic inspiration. Or perhaps use the melody but in a more syllabic fashion.