Christopher K. Wong argues that desirability is a key part of design that helps decide which features users really want:
To give a basic definition, desirability is a strategic part of UX that revolves around a single user question: Have you defined (and solved) the right problem for users?
In other words, before drawing a single box or arrow, have you done your research and discovery to know you’re solving a pain point?
The way the post is written makes it hard to get at a succinct definition, but here’s my take. Desirability is about ensuring a product or feature is truly wanted, needed, and chosen by users—not just visual appeal—making it a core pillar for impactful design decisions and prioritization. And designers should own this.

Want to have a strategic design voice at work? Talk about desirability
Desirability isn’t just about visual appeal: it’s one of the most important user factors