But what's weird is this sense of anger at products that aren't as flexible. It's like being upset that a new restaurant opened up because they have a set menu and don't let you make your own food. If you like cooking your own meals, great! Keep doing that. This restaurant is for people that want someone else to make a meal for them.
With slack I understand the frustration a little more, since it's something an entire company is going to be using and asking you to use.