You just bought a new smartphone. Since it's a phone, you figure making a call should be easy. Hmm...
Where's that button, icon, symbol, the word "Phone", whatever? You spend actual minutes trying, but can't find "it". You blame yourself. You get annoyed. Your intent to make a simple call - crushed. Your attention, time, energy and excitement - inexcusably stolen. How did that happen?
The user was forgotten during the time when the phone was designed. That resulted in bad design. Surprisingly, it happens a lot, especially in software.
I must fight for end users. My personality type* helps me do this. Reminding product makers of the value happy users through great designs makes me happy.