While I agree that form has (or can have) its own value, I reject the notion that "formal choreography can have a greater impact than any literal work." I think this is as off the mark as its opposite, that any work without content was a divertissement and unworthy of notice.
It's a popular, perhaps even dominant notion in critic/aesthetic circles, though, and has been for several decades now. At the Ashton conference a few years ago, I was told (I didn't go) that one of the younger panelists asked one of the oldsters, who'd been watching the Royal since the late 1930s, "Tell me, when was it that you realized abstract ballet was superior to narrative ballet?" She was still sputtering in protest a month later.
What do you think about this? Is abstract superior to narrative? Is narrative superior to abstract? Or is something superior to something else? Or not superior at all? Or whatever.