Design isn't about "rounded corners are better than square ones" It's communicating that "we are the kind of people who care about your experience" And that can be communicated through something as small as rounded corners
IMO one of the biggest barriers to creating great products is that the engineering mindset is about plowing through(fetishizing) difficult/painful problems which can see the designer mindset as entitled complaining. Synthesizing the two is hard and requires a kind of ‘love’.