[JaumeGreen]

Why should we?

I agree that it's trainable, but to create a good icon a first timer can spend several hours. Several hours in which they could be doing work that they have trained for.

If one intents to be a sole developer then yes, they have to improve in all fields, but when one is in a team one has to let some things go, and let people better than them on that field do them.

[seumars]

Design isn't about drawing pictograms, so nice strawman. The type of design thinking implied in the comment is more about knowing –or at least have the faintest idea about what a visually cohesive system is and could look like. There's no such thing as a "sole developer" in software development because your code is inherently tied to function and that function tied to its design. The more you value that concept the more you "train" your understanding of modern graphic design.