AI are actively trained to talk that way. They are trained on simulated conversations of helpful robot assistants, to sound like the robot assistant.

It is a neutral role with broad applicability. They could equally be trained for other styles. A model trained to talk as a pirate would get old, especially after it told you to bugger off when you asked for a cupcake recipe. A model trained to write like Hemingway would be frustrating when you want directions.

What would be better? who should it write like?

There is no technical challenge finetuning models to write in a specific style that is indistinguishable from a human