I'll bite.

The presentation for the Bookmark was at best horrible. Just by forcing the reader to repeatedly click on a specific point of the screen just to get a progressive sentence or two, just isn't a way to do it, especially if you don't even give an indicative of where you are at. I gave up at 20th click or so.

Second, let's examine how the link was titled:

  Show HN: Escape from Bookmark Hell

Escape from Hell already gives a connotation that the author believes that the pre-existing system(the bookmarks), which people have been using for a long time, is somehow Hellish and that it is so bad that it needs escaping from.

Of course, perhaps the author has found and solved a problem which none of us knew we had, but if it were a constructive progress, I'm fine with it. But when you have to click seven to eight times, past the buzzwords, just to see exactly what the author is claiming to be such inefficient system, and ten or so clicks furthermore for the proposed solution, it just reeks of arrogance.

At this point I simply pressed a 'back' button, got annoyed, and simply closed the tab, not averting my attention to it ever again.

Apart from a personal experience from the example, here are the takeaways:

I didn't like what I saw. I didn't like the presentation. Which is fine, you can't please everyone. But I did not leave a feedback. To the author of the Bookmark, I didn't exist, or in a way more relevant to a developer, the disgruntled user whose opinion is valuable in improving the product never reached the developer.

That's how unconcerned people usually react.

Instead, you have a group of passionate people who took their time to criticize and comment on the product and the presentation. You should really take it with a grain of salt.

Of course, there should be some assholes, but it's the internet, or even, a group of people. If you had thought somehow that academic developers were all nice and respectful, you would be very sorrily disappointed.

I have no idea if the OP is the author of the Bookmark thing, but normally, when people don't like what they see, they leave, lest leave a comment. Some of the examples the OP listed are actually pretty helpful comments, of this point has already been discussed.

A criticism is better than negligence. Almost always.