Sometimes I wish that severability clauses were not allowed in contracts of adhesion so that lawyers would be forced to only include terms that were actually enforceable or else have the entire contract become invalid. Obviously it wouldn't work very well if even a small mistake made in good faith could invalidate an entire contract, but the problem of companies hoodwinking customers with unenforceable terms has gotten out of hand.
In fact, they will frequently put in clauses that are known to be invalid, hoping that customers simply cave in when shown the clause.