@ Marvin
to be fair even the Jews much later didn't really stick to just pouring out the blood. Around Jesus time there were people who would collect blood running down the drain from the sacrifices and then sell it as fertilizer, making a profit.
I think I see where you're coming from now maybe, but I think it's a point that you'd really struggle to make with witnesses. As a witness I would have just said the point remains the sacred nature of life, the blood being respected was just a symbol of that sacredness. It really wasn't about the blood, it was about the life. Blood was being used as a symbol of life.
I would also have argued that the expounding on this law later by Moses showed that people weren't respecting life as much as they should have and so more specific restrictions were set. But blood was never the issue, it was only used as a symbol.
That would be my argument. I think coftys OP does a good job of sidestepping all such rebuttals.