That doesn't make you some champion of the working man, it makes you a cheap asshole. You are taking advantage of their labor more than the restaurant owner.

Advocate for change, absolutely. Refuse to patronize restaurants that expect/require tipping. I'd even say it's fair to stop buying into the tip-inflation (15% used to be standard, then 18, now 20+), that's fair, stick to 15%.

Hell, since at most restaurants you pay after the meal, why even pay that? After all, you knew there's a cost before you had the meal but "you can't spare it." I'm serious, you wan't to make a point, leaving a note that says "pay your staff better" and no cash makes a stronger statement than simply not tipping.