Maggie's Farm

Art must satisfy the needs of the patron.
A talented artist will also sneak in their stuff.

Michelangelo gave the Pope and the Medicis Classical respectability with a twist, and snuck in homoeroticism and his own tortured self-portrait.

In the modern era:
Photography + industrialization = realism and consumption for the masses.

So the modern patron's need is to distinguish themselves from an increasingly wealthy and educated populace.

Hence art spun away from realism and "common" taste, and dived into increasing abstruse ugliness that only the initiated elites can "appreciate". When every Joe can have a French Provincial dining set, a sterile home stripped of joyful ornament and furnished in modern brutalism signifies "taste" and status.

And artists = who had started styling themselves as revolutionaries and secular prophets instead of tradesmen-at-court - snuck in their deconstructionist agenda, making things even uglier.