We can argue all day about whether the Prequel Trilogy movies were good, but I don't see how some people are arguing that the weren't financially successful. All three of them are in the top 100 highest grossing films of all time (inflation adjusted). Episode 1 alone grossed over one billion dollars (in real dollars). These are movies that made absolutely bananas amounts of money. Obviously, everyone involved probably would have liked to make more money, but to suggest the Prequels were not financially successful is just way off the mark.
I don't know how much they made in licensed goods, and I'm sure it is much less over the long-haul than the Original Trilogy. However, the fact that they are still making Prequel toys suggests there's plenty of cash there.