Your mental models of the world are reflected in how you interact with it.

If you have an idea that there's a split between "creating beautiful stuff" and "creating useful stuff" then your world turns into one where something is only one or the other where someone creating only does one or the other.

These days it's thought of unique or special if something is both and the fact this isn't standard is influenced by the mental model of them being separate.

Moreover the people who create useful things don't often take the time to try to make them beautiful, with the result that everything is a utilitarian grey box with some buttons on it.