When you code, do you understand the asm code being built? What are the cache line access patterns? Most software developers have already given up the details of how things work, and lean on tools to handle them.

Which is fine, usually. Depends on what you are doing.

The things that always mattered were the core system, the trunk of a tree if you will. The branches less so, and the leaves not at all (though that is what people see and appreciate! The irony!).