Given all this, they did not exactly need their art to be a bummer too.

鉴于这一切，他们并不完全再需要艺术去表现某种失落。

exactly 跟 not 连用时，本身的意思是 “完全；全部” 。not exactly：不完全是。

ADV You use not exactly to indicate that a meaning or situation is slightly different from what people think or expect. 不完全是 

例：

He's not exactly homeless, he just hangs out in this park.

他不完全是无家可归，他只是常住在这个公园里。