As for Bono's guitar playing... I recall him doing some licks during the intro to Staring at the Sun on Popmart, and I thought he did them well. I remember him saying back in the 80s that he'd try and play Edge's guitar in rehearsals and despite putting his fingers in the same place as Edge he couldn't sound anything like him.
imho, you can't be playing a guitar for 30+ years or whatever and be considered a terrible one. That doesn't mean you're particularly great at it or high enough in the live level mix, of course. But if you play it enough, then you at least have some idea of what to do every time. And then playing like Edge or whatever will depend on their own unique take or proficiency with playing whatever it is exactly.