Is there any situation where you'd want to remember the opcodes? Disassemblers should give you user-friendly assembly code, without any need to look at the raw numbers. Maybe it's useful to remember which instructions are pseudo instructions (so you know stuff like jz (jump if zero) being the same as je (jump if equal) making it easier to understand the disassembly), but I don't think you need to remember the opcode numbers for that.

Edit: Maybe with malware analysis where the malware in question may be obfuscated in interesting ways to make the job of binary analysis harder?