The authors have to take the time to study the situation, talk about it, make hard decisions and cut out features that are useless or barely useful, and have th

The authors have to take the time to study the situation, talk about it, make hard decisions and cut out features that are useless or barely useful, and have the balls to ship a product with just the right features instead of all the features in an attempt to please everyone. Not the user. You're perfectly entitled to that view, and for someone who holds that view a product like Thunderbird is obviously not a good fit. There are, however, other views, and for someone who doesn't want simple UIs with no flexibility or configurability and doesn't have a problem with spending a few seconds customising something to get a result they are happier with, a product more like Thunderbird is a better fit.