What portion of the global population uses bitcoin, and is familiar with the word "sat"? 1%? 0.001%? Whatever it is, that is the extent to which "sat" is established.
Explaining what "sats" means to people who are new to Bitcoin, or even those who are not new to Bitcoin but are unfamiliar with "sat", is a tedious exercise, often met with confusion. It is not intuitive for them, nor easy to remember. If we just call the units bitcoins, that problem goes away; there would be nothing extra to remember. It is a lower cognitive load for new users. It also removes the "I can't afford a bitcoin" unit bias that a surprising number of people have.
