I like life imprisonment for heinous people specifically because it seems like the less merciful option. Look at how many mass shooters and terrorists also take their own lives during the act - suicide is one of their objectives. If we can capture them alive and make them live in a small room, eating unexciting food and sleeping on thin mattresses for decades still to come - that’s the ultimate rebuke to their ideologies of death. Execution, on the other hand, is giving them what they seek.
It can’t be explained directly, by itself. They’re part of a bigger picture.
Straight men are attracted to women on the whole - legs, arms, waist, face, chest, back, it’s all good. Whatever force it is that makes us attracted to women, it’s not something that we chose or decided. We just do.
Since boobs are a sign of femininity, they’re attractive to us on exactly that level! They fit into our idea of what women look like.