I worked out one time Ive more than 300 million online sales/signups/downloads under my belt. I like to think that gives me some credibility. And I agree with OP that simple, basic and even ugly pages can be extremely effective.
Design is incredibly undervalued on HN, and I make contrarian claims to not only ruffle a few feathers, but because it’s a fundamental thesis of mine.
Note aesthetics are also a functional beauty to me, I enjoy both refactoring code and typesetting a landing page as part of the design process.
Fwiw, I think you're right. 3x is probably what the match of design and message results in, especially because a lot of what software does can't be described merely in words. It needs design to put the accent on the right things, or else will fail to communicate (most of the time).
Looks like we're reading different HNs.