One issue I had with it, however, was that in a conventional sestina, it's pretty obvious from the start what one is doing; the form is like scaffolding left up on a building and to my eye, dominates the subject matter too much.That seems to apply to everything but the sonnet. (And the sonnet uses a rhyme scheme that English can handle, because it's not too far from the ballad abab that gave us our notions of what rhymed verse can do.) There's one villanelle- Do Not Go Gentle Into That Good Night- and one rondeau- In Flanders Fields- where the form is organic to the meaning. All the others- yes, the scaffolding shows.
Then again, maybe the sonnet exception is because some brilliant poets used it. There are innumerable lacklustre sonnets from the 16th century onwards, and if that was all I'd read, maybe I'd think the sonnet wasn't suited to English either.