As a person who chose to have an amputation, there are times that keeping the leg will result in a MUCH lower quality of life than loosing it. I had a bone issue that kept me either off my feet, in a walking boot, in a cast from the knee down, or in a wheelchair on & off for almost 10 years. I finally just decided to lose the leg altogether & it was one of the singularly greatest decisions that I ever made.
When I told my family my decision, it was amazing the differences in reactions. Those I was in regular contact with were extremely supportive & glad the previous issues were coming to an end, but extended family were absolutely horrified that I would consider "voluntarily ruining my life". Around the same time, a friend's cousin was told by his doctor that he would have to lose a couple of toes. The man, who was middle aged, couldn't deal with the thought, & actually ended his life over the idea of losing a body part. Another lady my brother works with had her ankle fused after a motorcycle accident, & told him that she wished she had the courage to have just had an amputation instead.
I guess my point is, I'm seeing about the same differing reactions online regarding Mr Renner, & I sincerely can say from my experience that it's all about attitude. My lifelong philosophy has been this-
If you have a problem & identify the problem, if you don't fix the problem, then YOU'RE the problem.
My leg was a problem, & it sounds like from his injuries, his could be one as well.