Calculate Field and all other geoprocessing tools that have a field choice-list have displayed field aliases since Pro 1.0, there hasn't been any recent change to this effect unless I am misunderstanding your comment.
You are right, in certain situations it's better to view the field name. However, field aliases are the defacto choice for listing fields across the app, so there is no setting for geoprocessing that will switch all field lists to display field names.
For calculate field there are two things that might help you --
1. In the choice-list for selecting a field, you can hover over the entries to see a popup that states the field name and alias.
2. In the expression builder Field Options you can toggle between field name and alias.