> This is something I notice here on HN in product-related discussions more and more: people just say what THEY think about product X (typically a negative opinion or complaint), rather being creative, constructive or inquisitive.

I think that's always been true, if anything it might have gotten a little better. I remember back in the early smartphone-wars days any article about the iPhone would illicit numerous "iPhone is too locked down" comments and any Android article would illicit numerous "The UI is bad" comments.

Somewhat related, the most influencial Paul Graham article for me is http://www.paulgraham.com/identity.html. I try (and often fail) to apply this when responding to articles.