Fundamentally Human
The two key drivers of emotion.
Building for every permitation of the human need or statistically picking features based on their conversion potential, is a fool's errant. What you can do, is understand how humans fundamentally experience products or services and systemically build on that foundation.
The question is not "Why do we buy products or use services?" or "What is your Job-to-be-done?", but how do people judge their experiences or more specifically, "What affect people's trust in you and your product?"
If you take a moment and go through all the available UX heuristics for digital products and consider what the fundamental human experiences are, which these rules-of-thumb wants to protect, you might notice two points of interest.
Firstly, experiences that affect people's "Sense of Agency" and secondly, experiences that affect people's "Sense of Value".
A "Sense of Agency" refers to the feeling of being in control in your life. When things don't work out as planned or you are not getting what you expect, it affects your sense of being in control.
Common examples would be: Not showing users where they are in an app or incessant unwanted notifications (which users can't stop) or tieing your marketing communications with
receiving your monthly statement or blocking a user from using a function, without indicating why.
A "sense of value" refers to the feeling of being appreciated, acknowledged or respected. When your time or effort is dismissed by a product as they frequently move things around (improving UX?), dismissing the effort you've put into learning it (agile anyone?) or send you an automated response to your lenghty, detailed email or giving you the same options irrespective of your choice. We are in essence communicating (through a thousand cuts) that their only value to us, is their money.
All of these experiences affects people's trust in us and our products, and without trust our only connection with the customer is hanging on to a single thread (which we defined), called "price".
In a "world of free" (choice), what are we really offering as value?