Madonna, religious imagery and controversy have gone hand in hand for over two decades now. people will complain about ANYTHING if you give them enough time to dwell on it.
in the end...if the "cross" means something to you, then won't it STILL mean the same thing regardless of whether or not someone else uses it in a way you find to be disrespectfull?
remember the "Like a Prayer" video? easily one of the most stunning videos she did during the 80s and full of a daring mix of sexuality, religious imagery and controversy- madonna covorting with a black jesus (among other things).
i think her LATEST "stunt" is not hardly as "eyebrow raising" as things she's done in the past. although the site of the "disco crucifix" was rather creative to me.
as a child, back here in metro detroit, Madonna (who personally recounted these events) ,whose father was a staunch catholic, would sometimes go to church with her family wearing nothing but a trench coat tied up with the belt. NO underwear or dress underneath. she often spoke of making love in a church.