Cusanus' philosophical emphasis on the mystery, the unknowability, of God, rhymes or complements the poet's unique sense of the difficulty of expression - its emotional basis, the sense that its authentic rewards must be earned.*
This encapsulates his appeal for me.
*(How else offer an adequate image - rather than a dry resume or empty abstraction - of experience? What other import is there for the notion of the image as an "emotional-intellectual complex", or Eliot's problem of "dissociation of sensibility"? & what drives this demand for wholeness in representation, but a notion of creative vitalism or spiritual wholeness as inherent to reality itself? I could easily wax polemical, too, about how poetry offers complex wholes, represents lived experience. This gets into issues of style. I won't go there now.)