I don't know. Maybe this impacts us so hard because the band is such a big part of our lives. Johnny Depp had similar claims levied against him in his divorce, and I had no issue watching Pirates of the Caribbean on TV the other day... But I can't bring myself to listen to STP anymore.
As someone who has known way too many victims of domestic abuse, the possibility that I've been such a fan of someone who may have done the things described is disgusts me. Dean's the reason I learned to play guitar... Now it's possible that he is an absolutely despicable human being. It makes me sick to my stomach.
As I've said before, whether these allegations are true or not is irrelevant to Dean's position in the band. If getting in a fistfight with Rob, as has been alleged, didn't get him fired than a minor public scandal won't. Dean's much less a celebrity than Johnny Depp, and Depp's still out their playing with Hollywood Vampires and filming Harry Potter prequels. The only thing that would get Dean fired would be if he were actually arrested.
So no, I guess this won't affect the band's legacy. But for me it killed my passion for the band. Maybe in the long run I can forgive and/or forget, but for I'm just dreadfully disappointed.