Incidentally, it isn't just modern (ie 21st century people) who are offended by Fagin's portrayal. A short time after Dickens wrote the novel, Jewish readers wrote to him to discuss their opinions of the character. So, the fact that Fagin is a Jewish stereotype (and the character's connection to Isaac Solomon, "Prince of Fences") has been realised for a long, long time. It isn't just something that's only been picked up on recently.