Kasparov V Deep Blue Game 1 thought?

You are right in that it was an orthodox move, he's trying to take the computer out of its opening book I presume (standard anti-computer strategy). I think it would be foolish for black to trade a developed bishop like that and doubled f pawns would hardly be a serious weakness at all in this position. He would merely exchange one for black's e pawn down the road. That's why the computer didn't choose this line.