A separate, heavily moderated forum on HN dedicated to product launches and feedback. Non-constructive criticism like "Your product sucks, it's a terrible idea and you're a terrible person for thinking of it" results in an HN hellban/permaban.
Myself - I'm not opposed to receiving negative feedback. It's the worthless, non-constructive feedback that riles me. Say something positive and/or insightful. Meaningless, parroted comments are what ultimately sinks an online community.