PREP has the potential to completely turn the tide on HIV infections. I live in a mid-sized midwestern city where between 10 and 25% of gay dudes in my dating pool are HIV+, many of them unknowingly and therefore continuing to spread it. There is a big push from the local public health department to get gay guys at risk of contracting HIV on PREP and it is starting to pay off.
PREP also is helping reduce the stigma of having HIV. Many people who are HIV+ live with a huge mental health burden of dealing with feeling like they are going to be rejected as a romantic partner because of their HIV status. With PREP as an option this helps reduce that burden. I'm not necessarily proud of this but I'm not sure if I would be dating my current boyfriend if PREP were not available because of the risk it could present to my health. He's an amazing guy and having this issue out of the way for us has been very helpful for us.
That's not to say that it doesn't have side effects and that it should be carefully considered but it really needs to be publicized more as a preventative treatment option in high risk populations.