Aside from "this is rubbish" the rest of that sounds very constructive.

Anyone with a product to share should want feedback. Doesn't mean that person needs to act on it.

Also, if you are criticized, take a second to think about it before immediately defending yourself.

The worst Show HN threads are where the OP feels the need to respond to every comment on the board to defend his or her project.

Learn to take the criticism.