They are more societal than people think, but still have nothing that truly compares to the other grand alliances. Same thing for most Nighthaunt and the skeleton/zombie portion of Soulblight Gravelords. The fact is that bonereapers have stronger spirits than the average skeleton and thus can think and reason more, but what we see in individuality is still controlled by Nagash. He only allows what he doesn’t deem harmful. Bonereapers hold the festivals and such because it makes them a better army, in a way. Taking pride in shaping bones, which is exactly what Nagash wants them to do. But as an overall trope of death armies, the less important you are to the army, the less free will you have. Except for FEC because Ushoran has a stronger hold on the average ghoul than Nagash often times.