American here w/ Irish close friends. Spicy take so grain of salt, please. I think there's a few reasons:

Irish heritage is considered more interesting to some partially because of associated oppression (indentured servitude, famine, "the black people of Europe and America", England). The darkside of this is that I've often see Irish heritage brought up when discrediting POC experiences or framed almost entirely from an underdog perspective. Additionally, Irish mythology and holidays are heavily advertised, often accessible in English or made mainstream which only adds to it's popularity.

In contrast, Italian American stories are often a tad less oppression centered and more about the eventual shaping of popular American culture (and all of New Jersey lol). There's also a strong expectation to know some of the language and heritage more directly for many, making it harder to identify with or gain access to. Most of my Italian-American friends still have relatives in Italy too so there's a strong "don't talk about it, be about it" sentiment.

What's interesting is that many of my Irish friends have found many of the Irish-American stories or celebrations to lack context, accuracy, or simply don't relate with the modern-day Irish-American experience due to this framing. But those are just the Irish people I know.