Design is not art
Design and art go hand in hand. But they're not the same thing.
When I was younger, I identified as a graphic designer. I'd design logos and flyers for nightclubs in Newcastle. When you're doing this kind of thing, the lines between art and design blur a lot. And, I have to be honest, I didn't know the difference.
I'd combine art with principles such as the golden ratio, irradiation phenomenon and overshoot. I'd pick typefaces to best represent the brand of the company I was designing for. There was some science to it, but it was still open to opinion. Somebody could still decide they didn't like my work. And clients often did.
Art is to be enjoyed
Art is meant to inspire those that connect with it. But, by that logic, not everyone will connect with it. This makes art subjective.
You can't gather evidence to prove that art is good or bad, and even famous artwork with legendary status could be viewed as terrible.
I remember in school, telling my teacher Pablo Picasso was rubbish. She was furious, but this was my opinion. If you don't like something, you just don't like it. And you can't argue with somebody's opinion.
Design is different
The purpose of a design is to be interacted with so that somebody can do something. For example. a door, a website, or a car.
If you design something badly, people notice. And, if you design something well, people should never know you were there. A bad design can disable somebody from completing a task. But the good thing about this, is that you can prove when it's bad.
For example, a door you have to push to open that has a pull handle. These always catch me out. You can tell it's a bad design by observing people using it. If 10 people go through it, and 9 of them try to pull it, then your design is bad. You can't argue with the observed evidence.
As designers, it's important that we always consider this. It's important that we don't just design things that we think are pretty. Sure, good design should have some aesthetics to it. Anybody that's held any Apple product will know how good it feels in your hands. But all too often, the usability is sacrificed for aesthetics.
We're in the unique position where we design things that make a difference to peoples lives. It's important to make sure that we research often. That we do the hard work to make it simple for those that use our products.
Make your door ugly, or make it pretty. But make damn sure it works!