Creative writing prompts: are they a crock?

In Introspections: American Poets on One of their Own Poems, Chase Twichell, poet of some renown and co-editor of the even more renowned The Practice of Poetry, makes a startling admission:

About a year ago, I did something dramatic: I impulsively destroyed fifteen months’ work. One morning I sat down at my desk and looked at the poems I’d written since the Ghost of Eden, and realized they disappointed me. Way up here in the mountains, we have to pay for our trash disposal by the pound, so everyone burns their nonrecyclable paper. In the yard, my husband was burning ours. With the thrill of rashness, I dumped the sheaf of poems into the barrel, then erased them from the floppy disk and hard drive. All this took less than two minutes. I actually broke into a light sweat, but it was the sweat of exhilaration, of freedom – I was back at the blank page, the threshold of the unknown. Since I hadn’t yet articulated what it was I next wanted to know, I’d been writing poems that hadn’t taught me anything and that ultimately bored me. So I burned them, and never thought about them again.

The Practice of Poetry is, as anyone in the know will tell you, one of the workshop bibles. Basically it's a compendium of poetry writing prompts -- jumpstarts to overcome dreaded writer's block and get you going -- by some of the most famous teachers in the business. Yet I find it particularly telling that the editor of this same book can fall into the funk of writing poems over a long period that, as she put it, "hadn't taught me anything and that ultimately bored me." Are these creative writing prompts all that they're cracked up to be? Of course, no one ever claimed guarantees. Maybe doing something as radical as jettisoning over a year's work will make it into the next edition.

I myself have found The Practice of Poetry quite useful -- the first exercise, Thomas Lux's "Not-So-Automatic Automatic Writing Exercise", spurred me to riff out not a few of my best prose poems, although I never, beyond numerous drafts, got to Lux's winnowing Not-So-Automatic part. Frankly, though, I've never really gotten past that first exercise. Everything else I've tried in that book, "ultimately bored me". Maybe this is from lack of trying -- but it always strikes me with these prompts that a crucial element is missing: should I call it fire? Reams and reams of so-called poetry may get cranked out in the writing workshop industry, but nothing, it seems, will take away from the rarity of the truly inspired poem.