Yeah, getting a bad flu is not fun. It has been more than five years since I've had the sort of flu in which I ended up over a toilet with stuff coming out both ends.
I think a lot of people would get the flu shot if they thought it could prevent that with a high level of efficacy. However, from what I've read, the flu shot doesn't have a good record over the past number of years of even correctly identifying the strains that traveled thru California. I remember a lot of people who had the shot still getting a nasty flu two years ago.