I've been watching this thread, wasn't going to post, but figured I'd offer my perspective.
I am a home mechanic/DIYer. I don't have a SO dealer. Pretty much the only way I buy SO tools is secondhand, either on here, at the flea market, or a pawn shop. Not with the intent of buying a broken tool and sending it in for a new one, but because my budget simply doesn't allow for me to buy new. The SO tools I've bought in the past were purchased because I know they are of exceptional quality. I've never broken a Snap On tool.
Having said all of that, this policy (or rather, the enforcement of this policy) makes it significantly less attractive for me to buy Snap On tools. Knowing that I may not get warranty service if I break a tool is a concern.
Now, I realize that me and people like me represent a tiny, tiny portion of Snap On's overall market. And we represent exactly zero revenue to the company and it's network of dealers. So I am not surprised, or upset, with SO for doing this. It just makes it less likely that I will buy Snap On in the future.
If I was turning wrenches for a living, at a shop, and had a dealer, it would be a different story.