The first reason is that after the first couple they become formulaic and encourage formulaic writing. It's simple: Hook the reader with the opening, take a few turns, end with a surprise. The reason for this is simple: most of the people in the workshops don't "get" poetry, never will. But most of them are intelligent enough to learn some craft and well-crafted lousy poems are IN. Also, without lots of pretenders, who is going to support the writers running the workshops, many of whom are in fact pretty good poets? Anyway, I noticed after several workshop experiences that on looking back at my old poetry I was writing better but without the same passion. I asked poet Peter Liotta (a genuinely good poet of the highest order) how to retrieve the passion and he urged me to get out of the workshops; I had done enough of them. That was the last workshop I ever went to with the intention or hope of getting anything from them. The advice has proved itself excellent.
Next post-- part 2
So long for now.