Presidents attending is actually not that common.
POTUS at the Army-Navy Game
1901: Theodore Roosevelt – Army, 11-5
1905: Theodore Roosevelt – Tie, 6-6
1913: Woodrow Wilson – Army, 22-9
1924: Calvin Coolidge – Army, 12-0
1945: Harry Truman – Army, 32-13
1946: Harry Truman – Army, 21-18
1947: Harry Truman – Army, 21-0
1948: Harry Truman – Tie, 21-21
1949: Harry Truman – Army, 38-0
1950: Harry Truman – Navy, 14-2
1952: Harry Truman – Navy, 7-0
1961: John F. Kennedy – Navy, 13-7
1962: John F. Kennedy – Navy, 34-14
1974: Gerald Ford – Navy, 19-0
1996: Bill Clinton – Army, 28-24
2001: George W. Bush – Army, 26-17
2004: George W. Bush – Navy, 42-13
2008: George W. Bush – Navy, 34-0
2011: Barack Obama – Navy, 27-21
2016: Trump - Army, 21-17