According to Wikipedia, Austrian Emperor Joseph II was very much interested in establishing the Singspiel, a German language musical theater, in the Austrian capital. This theater form descended from the English ballad opera and the opera comique of Paris and was considered a popular entertainment with simple songs.
One of the Singspiel commissioned for Vienna was Mozart's Abduction from the Seraglio, an opera written in German with spoken German dialog.
So here is the quote: "The Emperor Joseph II commissioned the creation of The abduction from the Seraglio, but when he heard it, he complained to Mozart, 'That is too fine for my ears — there are too many notes.' Mozart replied, 'There are just as many notes as there should be.'"
So let's suppose the Emperor was not an idiot. What he got from Mozart was an Italian opera translated into German with all the set piece coloratura arias one would have expected from an Italian opera and not at all the sort of ballad-like numbers expected of a Singspiel. He paid for a Singspiel and had every right to expect to receive one. I think it's time to stop picking on him.