I've been been hinting at posting some ideas from a recent term paper here. I'm not sure if there's any interest, but I'll post some thoughts anyways.
Everyone who offers analysis of Portrait of the Artist as a Young Man says Stephen is James Joyce. Given that they live in the same places, go to the same schools (with the single notable exception of Joyce's time with the Christian Brothers), and have the same general life experiences. Everyone is right to see Joyce in Stephen.
Stephen is another symbol too—for Ireland. His pride is Irish nationalism, his culture Irish culture, his internal conflict Ireland's internal conflict. He is torn between multiple paths towards the future, and as much as he wants to forge his own path, he eventually simply absorbs the paths of his influences.
Like Ireland, Stephen's pride defines him. Especially towards around the turn of the 20th Century, Ireland was awash in nationalist sentiment and revival. The language and practices of lore were renewed and new hopes for home rule or even independence emerged. At the same time, Ireland remained largely blind to the issues that the conflicting movements of nationalism in Ireland brought. Despite both wanting independence, tension continued between the urban and rural citizens, even as the distinction became less important. Yet the people saw themselves essentially as one people and one nation. Stephen's pride blinds him similarly. He does not notice his inability to grasp certain ideas and cannot converse well with anyone he holds inferior, even when they have wisdom to offer him. Any threat to his born nobility is a threat to his entire person and culture, even though his family had long ago joined the middle class.
Stephen desires to be an ideal Gaellic boy, but also must acknowledge the benefits of English culture. He wants to assert his own identity, but wants that identity to conform with the surrounding notions of what it should be. As Ireland moved towards independence in the early 1900s, it faced a similar challenge of becoming a proper European country, while also staying true to the nationalist sentiment that birthed it.
The other thing I think people miss is that Stephen isn't Dadalus. Simon, Stephen's father, is Dadalus. Stephen is his son, Icarus, dated to lose his life to his pride. Joyce is warning Ireland, telling the homeland he left behind that if it does not check it's pride, it may burn to the ground like Icarus. Stepehen ist leave the island to save himself, just like Joyce thought Ireland must look beyond it's own shores for answers to the questions it faced.
Maybe no one talks about this because it is too obvious, too simplistic. In my research, it was fascinating to see how ideas about the book developed over time. Early critics were much more critical of Stephen, quick to point out his faults, especially his pride. More recent ones seem more concerned with other parts of the book, but tend to view Stephen more positively when they do mention his characterization. I think both groups miss the point though. Stephen, as the Artist and the Young Man, is the focus of the novel, but he is also positive role, whose message lies in his potential for tragedy.