Embarrassed by how much I miss Twitter's quote-tweet feature on here. It was mostly used for evil but I tried to use it for good!!
"I miss it as a writer but I enjoy its absence as a reader"
--- brilliant.
That really is the deeper cultural rationale for a no-QT policy: it respects the reader (of the original post) over the writer (of the reply).
The lack of QT forces the writer of the reply to be more of a reader of the original post. Therein lies the source of true dialogue. Be a reader first.