I always do the keywords tag. You never know if one day the major SEs will start using keywords again. It's also possible they are still using them to a degree but that information is not disclosed.
What harm does it do anyway? It's just a small one-time job which takes a minute to finish.
Another benefit is it can get you thinking about non-obvious keywords you may not have included in your content area or meta desription which you can then add.