Let's be clear, I love API commerce. API-First is clearly the best approach for a commerce implementation today. API-Only definitely has a place in the market. With that said, the term headless commerce needs to go.
The term headless is clear as a descriptor, it's whatever we are talking about but used specifically without a head. Headless Shrimp, buying shrimp where the head has already been cut off. Headless horseman, a horseman with no head. Headless guitar, a guitar without a headstock. All of these are arguably better without a head and no one tries to add the head back on.
In the technology space, the term headless has been used for decades, the head is ubiquitous with a UI layer.
Headless computers are designed to operate without a monitor, keyboard, or mouse. Note that they are not decoupled, that would be a standard desktop where the monitor, keyboard, and mouse are separate hardware devices.
Headless browsers have no GUI. They are great for running tests, scraping websites, and automating processes. This is not a browser where the GUI is decoupled or added later, there is no GUI at all.
Headless software in general is well defined as software with no GUI.
At first blush, this seems like a great descriptor for a commerce platform that only has an API (API-Only commerce). It is being sold with no UI layer, so why not call it headless? The problem is that headless computers, headless browsers, and headless software provide real value without a UI. Try to create an e-commerce experience without a UI layer and you will make absolutely no money.
So the very first question when building a "headless" commerce solution is, "what will we use for the front-end?"
This is in stark contrast to the other headless offerings, where a front-end is never discussed, asked for, or desired.
Unfortunately, API-Commerce doesn't have the same pizzazz as headless commerce. Marketing departments can't optimize for API-Commerce and it makes it clear that this wasn't recently invented, but has been around since the days of AJAX. So chances are this term is here to stay.
I will be holding out hope. Gartner correctly refers to this trend as "API-Based Digital Commerce" and in their latest Hype Cycle show it leaving its peak. The hype is fading, so as marketing machines move on to the next shiny term we can hopefully let "headless" commerce slowly fade away.