This is kind of my point - we would like developers to learn this kind of stuff but there is no financial incentive even if it is good for their employers. There are a lot of facets to our work that are like this, for example some soft skills would be in this bucket, except for the soft skills linked to becoming a 'team leader'.
Why would someone only do something for money? Well perhaps they have time and money commitments that makes it hard to justify doing stuff that is not for money, unless it is super important for some other reason. So charity work might trump learning visual design, but visual design is also trumped by learning React because that looks hot on the CV.