masked operations are really useful for dealing with the tail of loops. You can add a single masked instruction to deal with the last few elements rather than h

masked operations are really useful for dealing with the tail of loops. You can add a single masked instruction to deal with the last few elements rather than having to do a scalar loop at the end to deal with the bits that don't fit nicely into a register. Doubling the number of registers is also great. It's basically free (since CPUS have lots of virtual registers) and can lead to way fewer load and store instructions. Most importantly, these changes are basically free from an area and power perspective. A 2x wider register will give you ~1.8x better performance, but it typically comes with ~1.5x higher power and wasted silicon for non-vectorized code. EVEX gives you all the really nice to have features that might only give you 20% better performance, but do so while lowering power and not taking up extra die area.