The intention of copyright is ..."to promote the progress of science and useful arts". I don't see anything in there about rewarding 'work' irrespective of whether that work involves any kind of creativity.

Not sure where you got that quote from, but I'd say the work aspect is implicit in the "promote the progress" - ie progress requires that people are able to get paid in their work to progress science or the useful arts.

If the progress was trivial and required no work then it wouldn't need protection or promotion.

And sure it's phrased that way to get the balance between fair use and protection - but if there was no need of protection then copyright wouldn't need to exist - as free reuse is the default.