Hi, thanks for the feedback here. We mentioned the interactive display piece in the section on sharing the dashboard. Interactivity is important for a dashboard, especially in this day and age.
1) As you mentioned, they're visually pleasing. No, that doesn't make up for when it's hard to read data, but I think a case can be made for snagging people's attention and getting eyeballs on a report you send out. If a pie chart is the hook that gets people interested in your data, maybe it's a sacrifice worth making. Artists aren't the only people who can find things visually appealing.
2) Basically, storytelling. There's no rule that says you can't show the same/similar data in different ways to help tell a good story. In some situations, it could make sense to start with a high-level visual breakdown of a group, and then use more detailed charts to get into the details you want to focus on (like how different segments relate). Or maybe the story I'm trying to tell has a ton of sub-groups which all pale in comparison to one dominant one. I think a pie chart visualizes that situation (where exact details aren't important) pretty well.
I ultimately just don't think it's a binary thing, where only artists will enjoy having a little visual variety and that any and every pie chart is a 100% waste of everyone's time. Most of the time, they're silly and an excuse for different shapes and colors, but I like to think even pie charts have their place in data visualization.