Why are we still cherishing self-conscious 1916 Proclamation?

In my nationalist boyhood, one of my party pieces was declaiming Patrick Pearse’s oration at the grave of O’Donovan Rossa. It never occurred to me that I should recite the 1916 Proclamation as an encore, despite Pearse’s significant input into the latter.
The 1915 oration is generally seen as a dry run for the Easter 1916 document, yet the two could hardly be more different. The oration is splendid nationalist rhetoric, personal and passionate, with its memorable “Fenian dead” climax.