I always thought Audioslave was superior to both RATM and Soundgarden.
I remember a similar level of bemoaning the death of Layne Staley. I think for many people these were formative bands (I was definitely a grunge/alternative kid in the 90's), and it's partly the death of childhood heroes.
I think it's harder here because it's a man who fought his whole life eventually succumbing to his demons. It's also pointed because you've had a whole bunch of popular influential rockers from the early 90's self-destruct in various ways - Cobain, Shannon Moon, Layne Staley, Scott Weiland, and now Chris Cornell.