Creatives are usually allergic to other people's opinion. They tend to avoid hearing what others think about their ideas. But the truth is, it's essential to their task.
Designers' egos can be very fragile, and it's also true that, historically, creatives have been very nasty with each other when it comes to criticing their work. Even with that in mind, it worths making an effort and trying to nurture a culture where feedback is heard and wanted.
You might think; why is feedback so crucial for design teams? Well, let me tell you some of the reasons.
First of all, no man is an island. And no creative team should entirely create alone. There are many reasons why this is important. Design and creative teams work with a goal and an audience in mine. They have to consider certain things, and that requires hearing other people's opinion. Including colleagues, users and even clients in your process is a healthy habit.
Secondly, when colleagues give feedback to each other, it means the level of trust and respect is high. You wouldn't care to listen to the opinions of someone you don't appreciate, right?
And finally, teams that practice feedback correctly genuinely know how to co-create. Ownership dilutes, and the focus is on building great things, not inflating anyone's ego by appropriating everyone's idea.