These beacons are also great for navigation. Aeronautical charts usually show the color/pattern of the light. You can use those as points to triangulate your position.
It can be really confusing approaching a port at night. Never mind the city lights behind, and the cars driving about. 20+ lights flashing at different rates in the dark, some of them disappearing for seconds at a time. Oh, and if you turn your light on to refer to the chart, there goes your night vision!
Boat masts above 25m also have blinking red lights for the low flying aircraft (I guess its a bragging point)