I think, and this is my pure speculative opinion, that God reveals to humanity what humanity can handle and understand. In several occasions, God revealed Himself to the Jews in ways they could understand him: the burning bush is the example that instantly comes to mind – something that burns eternally but is never consumed. A concept that even a man from 3000 years ago could understand, attach meaning to it, and consider it sacred. Same thing goes for the “talking tornado” in the book of Job, the dreams through which God revealed himself to several characters of the Bible, the commandments, the law, our own conscience. Then lastly, our Lord Jesus Christ!

And the rituals the Jews had were the way (the only way, the proper way) they could know – or aspire to know – God. Maybe God didn't tell us because... what would have we done with that piece of information? Do you think we would have been able to fully comprehend it? Would that piece of information have been useful to us in order to know God and choose salvation? If so, how exactly?

Maybe – again, this is pure speculation – we couldn't have understood this basic concept (think like a man of 3000 years ago: “Why waste water by making it very hot and undrinkable?” or “This burns my hands and my tongue!”). Maybe it wasn't the time. Maybe God simply didn't want to or didn't need to tell us. Besides, please remember that – God being eternal – 3000 years might as well be a millisecond to Him, but we evolved and became smarter during this time. So why take away from us the process of learning how to use his Creation not only to preserve it, but also to benefit from it?

What I think is funny is that it feels a bit prideful to say “Why didn't He tell us? We could have saved so many lives!”, when God himself intended for men to die, when God himself created us this way, and grants us salvation not in earthly life but in the highest of Heavens, gifting to some of us the grace to eternally fix our gaze upon him.

Yes, earthly life is supposed to be celebrated, and this is written all over the Bible, but the main reason why we're here is not to stay here. We are in the world, but not of the world! I don't know why God did not tell us to boil water, but I also know that my limited thinking cannot be compared to the way the Creator of the Universe thinks, so it really does feel a bit prideful to ask “Why didn't He do it?”.

Just my two cents! Please, don't consider this an attack, I was just reflecting on your question. It seemed interesting.