A couple of companies have been burned by that when a large number of customers all filed for arbitration at the same time. Because the company is responsible for the arbitration costs, it quickly became much more expensive than defending a class action lawsuit would have been. Arbitration is good if you're only expecting random one-off lawsuits here and there but if you're going to anger a large number of people, using it as an alternative to the legal system can quickly backfire.