Why learning assembly language is good for malware analysis

Usually when an attacker/malware author compiles his code using any number of compiled languages they end up with a machine executable format.
When an defender/malware analyst wants to disassemble this arcane mumbo jumbo machine executable format into a human readable format. The dis-assembler produces assembly language as its final product. You can read more about digital forensics at Lenny Zeltser's SAN forensics page here.