I've never understood why people who are otherwise for vaccines are anti flu vaccine. It's weird - you have less of a chance of getting the flu than if you didn't take it (and that chance varies a bit from year to year), but you're still coming out ahead by getting it, and helping reduce the spread.
I mean, people die every year from the flu. There are unnecessary hospitalizations that could be cut back on by taking the flu vaccine.
Insanely, even my wife is on the 'it's not necessary' side. Sure, the chances of us catching the flu and contracting a serious side effect aren't great. But when you can reduce that chance with basically no downside, I don't know why you wouldn't take it (and it's completely free here too).