I haven't attempted prose and so my comments only refer to poetry. Then again, perhaps they should be more limited to light verse....
However, I believe the current thrust that takes the writing of both prose and poetry to promote terseness justifies deep thought.
I see it as practical for prose in that prose is the language of law and clear communications and as such should promote full understanding with efficient usage of words.
Poetry contains a far greater element of beauty at the expense of clarity and terseness. Thus I reject the thought that terseness should be an element of poetry.
I believe the commitment to terseness results solely from the modern attitude about poetry, that is, IT SHOULD BE MORE LIKE PROSE!
I want my verse to be as far removed from most elements of prose as possible. I want it to sing to you. I want it to make you smile. I want it to appeal to your emotions. I don't want its form to be restricted by a long list of no-nos that make accomplishing those goals more difficult. Terseness in poetry is to me an intolerable and valueless constraint.
Read Longfellow's "The Day Is Done". It is chock full of little, unimportant words, "the", "of", "and", yet for me, its perfect simplicity and sincerity penetrates my shell and so represents the essence of what poetry should be.
I don't know who the folks are who are considered the Shepherds of poetry, but I am not one of their flock!!!
Cheers, Ron jgd