Yeah, what if Bono did just go back to wearing a cross like in the JT days, many Protestants wear cross necklaces, and it's generally just to remind oneselve of what you are. Perhaps it could be argued, if you are (fill in the blank), why would you need a reminder. I guess to non-Christians, the wearing of crosses is kinda bizarre, but it's just a simple reminder of what was done, (as the Christian faith states) for us. It could be said, this is why Bono wears it as a necklace, as many Protestants, wear cross necklaces. He was raised Protestant, so maybe the "don't wear the Rosary" as a necklace, wasn't part of his upbringing.
I do wear a beaded necklace with one of those "Jesus" fishes on it, but I wear it because of the meaning behind it, not because it's "fashionable." Then again, when has it ever been "fashionable" to be Christian.
Anyway, the story (well it's what I heard), behind the "fish" symbol, was that it was a sign to let other Christians know you were one, back in the Roman empire when Christian persecution was extremely high and violent. To find out if someone was a Christian, they draw in the sand, basically half of the fish. *Think of slightly long letter "C"* If the other person was Christian, they'd complete the other half, to make the "fish." If the person didn't, didn't know what it was, no big deal, went their separate ways.
I'm thinking it's clearly where the phrase, "drawing your fish in the sand" comes from.
Lots of people know what the "Jesus" fish represents, plus it's doesn't lead to that annoying "why not wear a gun around your neck," some people ask when someone wears a cross necklace.