Each time, I'm inclined to dismiss these messages. They make me think "well, I don't want to work with you because you sound like an uptight asshole who insists on everyone wearing a suit to maintain decorum, and no hats indoors". I end up feeling that we would not get along at all in real life, and I (usually) ignore the message and (sometimes) scoff.
But every time, there is a minor host of "thank you for expressing exactly how I feel about this" messages beneath, and frequently the comment is highly upvoted, so, I am now forced to confront the facts: that you are not a bad person, that you probably aren't as rare as I imagine, and that you (and authors of similar posts) are probably a perfect pleasure to know and to work with. We just hold different preferences -- both of which are equally valid.
To express my own: I like most of the structural elements of slack. I am not bothered by the interruptions it can cause. I send short streams of messages sometimes because I feel it can convey useful information about how the thoughts were chunked.
I am also (hopefully) not a bad person or a pain to work with, but might come off as such to you, were I to merely state my opposing preferences as fact or to note that slack's support for them makes it great.
Perhaps slack should change, or another product should fill that gap. Perhaps there are other groups with preferences that don't align with you or me at all! Either way, I find these thoughts much more interesting and healthy than imagining that I might dislike you, which was my former attitude. So, thanks. :)