If I owned one of these filters I probably wouldn't stop using it to be honest. Although it doesn't live up to the company claims against viruses, it's still effective against bacteria and cysts, and that's all I use filters for anyway. None of the other popular filters are effective against viruses either (sawyer mini, squeeze, lifestraw, etc) and never have been.
Since filters generally do not cover the full spectrum of threats, it's always a good idea to use filters only as part of a system and either chemically treat or boil in addition to filtering.
Of course your average casual outdoorsmen may not be privy to such details and think they can just buy this and it will make their water completely safe -- so I can definitely see why it's a big deal that their claims do not match the performance! Holy litigation issues batman.
As far as viruses being common in the US, it's becoming more widespread. Areas that were essentially virus free a few years ago might not be anymore. Besides that, it's not just a matter of avid outdoorsmen venturing deep into pristine wilderness -- many hikers and backpackers use well traveled trails, and there are a lot of urban "preppers" who rarely actually go out and use this stuff but keep it for emergencies.
Pretty much anywhere where there are humans, there are viruses -- and not just urban population centers, even popular outdoor recreational areas. Well traveled trails, parks, etc. Besides, how far away is far enough? When do the viruses stop and the clean water starts? You can't see them, so it's best to just assume they are there and operate accordingly.
http://globalhydration.com/blog/are-there-viruses-our-recreational-lakes-rivers-and-streams