Knowing how people will use something is essential
To me, error analysis is the sweet spot for improvement.
I prefer design by experts - by people who know what they are doing
Behavioral design is all about feeling in control. Includes: usability, understanding, but also the feel.
The design of everyday things is in great danger of becoming the design of superfluous, overloaded, unnecessary things.
When you have trouble with things—whether it's figuring out whether to push or pull a door or the arbitrary vagaries of the modern computer and electronics industries—it's not your fault. Don't blame yourself: blame the designer.