Many Irish-American pols foolishly thought a top hat symbolized ethnic arrival in the USA. Like...look at me I made it! While JFK came from a privileged family (both his father and grandfather Honey Fitz wore top hats) he was well aware of what it symbolized in the Irish-Catholic community. He ultimately kept w/ tradition & wore it to his inauguration. When Mamie Eisenhower saw her husband Ike in a top hat for the inauguration she uttered the ethnic slur, "he looks just like Paddy the Irishman. "
The election of JFK meant that Irish-Americans were finally unequivocally American. Although he fealt uncomfortable wearing the hat it did provide him with the opportunity to tip it to his father Joseph P. Kennedy.