In order: 1. Because people make mistakes. I am, as of the last check, still a member of that classification. A total cartridge weight check is a QC double-check. It's not sufficient by itself. It can be a useful backstop.
2. So that the final weight of the cartridge has meaning (see prior post)! And so that if problems manifest with a particular brand/headstamp of brass, it's easy to segregate both loaded and unloaded cases with that brass.
I wouldnt say that I am willing to take risks, I am just very comfortable with the way I reload. I am satisfied that I do not have critical errors in my process.ljnowell, I get the sense that you're a little less risk-averse than I am. But I'm not trying to reload at fastest-possible safe speed. I'm reloading, in part, to unwind after a long day. If I load 30 rounds in 45 minutes, I'm ok with that. I enjoy the process.