A lot of people DO NOT get the flu anyway and even parts of the vaccine not specific for new strains help some. See above; there are few reasons to avoid it.
I said if you are susceptible and/or have a weak immune system then the vaccine won't be much help, that is proven. The young and elderly should take it as a precaution but if you are a healthy adult, it isn't the end of the world if you don't get the vaccine.
They mutate so fast, so the vaccines are for different strains. It is a great preventive tool for those that are unhealthy. The latest study shows that the vaccine is effective about 77% better but that is for a healthy adult, not elderly or children.
I am no doc like you but I have taken my fair share of microbiology classes from undergrad to med school giving me a pretty good understanding of this
I guess that I am still old school where we used to play outside as kids, get nails stuck in our feet and scratched from fences where we built our immune systems. My generation never took shots for this and most other stuff and we can fight off most colds and the flu