The use of Consul as a title has pretty much the same explanation as why America has a Senate-classicalism and veneration of the Roman Republic was very big among Enlightenment intellectual and republicans.

As for Emperor-to contemporary's it wouldn't really have read as a roman title. After all, one of Napoleon's main geopolitical enemies was the Holy Roman Emperor and Archduke of Austria (and the abolition of the Holy Roman Empire came about in no small party out of fear that Napoleon would claim that title as well.)