I'd say it's the principle of the thing. Successful businesses are supposed to get that way by serving their customers - that would be the origin of the term "customer service" - and not by ripping them off or giving them the runaround. Unfortunately a lot of otherwise good companies (and also some bad ones) seem to have gotten this concept all twisted around backwards lately.

IMO, there's really no excuse for Master Lock's reluctance to adequately and honestly address this issue; they're a big company, and I'm sure they'll survive if they have to replace a few defective locks for free. And I'm sure their customer's brand loyalty would be a lot higher if they would just have been honest and forthright about this issue from the get go.