+ One one what Bruce says. There is more than that involved as well in my experience. I have done enough remodeling in old houses to know that the lumber was in consistent in sizes. It was common to find 2 X 4's that were over 2" thick and over 4" on depth. This wasn't so much a problem with lathe and plaster construction because a skilled plasterer (if that's a word) could make it look great. However when you rip that out in a remodeling project and then try to go back with sheet rock it required shimming and much trial and error to get it to work out. So creating a standard to follow was a win for everyone in my opinion. It was common to hear it said when I was younger that "they don't build them like they used to". My thought when it comes to this part of it is THANK GOD. Because were they a pain from the inconsistent lumber sizes and they generally weren't square either. Maybe this isn't the case everywhere but it certainly was in this geographical region. I am adding a link from an architect site that gives the standards for soft wood lumber. These lawsuits are nothing more than lawyers trying to fill their pockets. I have a hard time seeing where anyone was harmed here.
archtoolbox.com/materials-systems/wood-plastic-composites/dimensional-lumber-sizes-nominal-vs-actual.html