I will agree with swag and Senor Canardo here. Mexes is someone who spends too much time worrying about his hair and his physical appearance on the field. He is a show-off that doesn't play with his heart outside the shirt and he won't add stability to a back four the way Thuram does. As for picking Boumsong, that one is hard to defend I must say but I guess it is like Canardo said, he is someone who will not cause trouble over sitting at the bench for the entire tournament.
Cutting Mexes is the one controversial pick I will defend though. Not having Clichy, Sagna, Flamini and Trez in there is simply sad and Domenech indeed cannot be well mentally.