Actually, sometimes it is. Volkswagen got sued in the US for selling cars equipped with transponder keys that were far more difficult and expensive to replace than standard car keys without making adequate disclosures to the customer. I suspect a similar lawsuit option exists for Ubisoft customers.
Sometimes it's cheaper than paying the lawyers. The settlement terms in the VW case mostly consisted of informing customers who could make keys for them, and giving vouchers to certain customers for reduced-price duplicates.
Depending on whether Ubisoft really sees this DRM strategy as critical to its survival, it might settle such a suit, or try to head one off before it got to court by changing its DRM policy.
