I agree that Thrawn was made during the "what if space nazis sometimes cool actually" era of Star Wars EU fiction and that giving him poise, dignity, competence, intellect, patience, and even (to some extent) concern for his subordinates was part of that Rommelization of the otherwise-not-shown-that-way space nazis.

That's how he was written, unfortunately. As-is, on paper, he's a nazi but deliberately designed to be a charismatic and less-directly-inept-than-most nazi.