Prufrock: The most shocking line in English poetry

It's sort of a mystery to me why T.S. Eliot's "The Love Song of J. Alfred Prufrock" was the ultimate cool poem for the literary intellectuals of my day - when we were in high school (and before we read Howl, I suspect). How much of it could we have comprehended? And I don't mean on a literal level: the poem appears daunting at first reading, but once you realize that it's all the personal reflections of a single narrator and that it's constructed in a series of scenes, visions, observations, and self-realizations, that his mind moves forward and backward through a series of emotions - from hope to despair, by the famous concluding lines (human voices wake us and we drown) - it's not a particularly difficult poem. The language is pretty simple, the allusions are far from obscure, even to a high-school sophomore (then, at least). So what was cool about it? First of all, I suspect that the very contemptuous tone of a young author (and reader) toward an elderly man too timid and socially inhibited to take any action: intellectual, emotional, sexual. We weren't going to be like him. We wouldn't measure out our lives in coffee spoons. Second, I for one was struck by the language - and still am. I've said before (though maybe not on this blog) that I think the 3rd line of Prufrock is the most shocking line of poetry in English literature. After the sing-song opening couplet that almost sounds like opening to a children's book of adventure or rhyme: Let us go then you and I /when the evening is spread out against the sky" - then comes the shocker" "like a patient etherised upon a table." This line tells us that this poem will break with all convention, that literature will hereafter never be the same: a couple can dissolve, the meter can be smashed, the rhyme scheme abandoned, and the use of simile can and must be astonishing. Who would have thought that's where Eliot would be going? Later in the poem he compares the fog to a cat, nuzzling and licking - far more conventional and less disconcerting - and I think he does so to show that he can, if he wishes, use metaphor in a more conventional manner. But the evening spread out like an etherised patient shows that metaphor is a weapon of attack on our sensibilities: it's an image that on one level makes no sense and is hard to even envision - what exactly do you see when you picture the evening like an etherised patient? - but also shows a glimpse of a dying, menacing, frightful world beneath and behind the conventional view of things - societal, and literary.