Various writers attempt, each year, to answer the question.
… “St. Joyce has replaced St. Patrick in the new, post-Catholic Ireland,” the columnist and critic Fintan O’Toole once quipped to me.
That doesn’t explain the many who will gather in American cities to observe Bloomsday. There will be dramatic readings, broadcast on the Web, in various theaters up and down New York’s Broadway and special commemorations at Philadelphia’s Rosenbach Museum & Library, where the autographed manuscript copy of “Ulysses” is housed. Many will listen to the readings and lectures because they’ve never read the apotheosis of high modernism. In fact, the book may grow more inaccessible each year, since most young readers lack the grounding in the classics that Joyce took for granted in his future audience.
Declan Kiberd, the most original of contemporary commentators on Joyce, speculates that the enduring appeal of “Ulysses” rests in the author’s egalitarian impulse that transformed the ordinary into the epic; that ended in quiet fellowship between the petty bourgeoisie Bloom and the poet, Stephen Dedalus; with Molly’s deathlessly erotic monologue and the realization that she loves Leopold still…
Tim Rutten, Los Angeles Times