I'm not a lawyer, but I'm going to do my best at explaining why all of this matters.
The act, as you say, is rather short. That's the legislative framework, and the regulations are really how you operationalize that. They will set, then, the minimum standards, the minimal threshold for water. They will set defined service levels, defined accountabilities when something goes wrong, such as who needs to take action. It's really how you operationalize the legislative framework that's outlined in the act. That's the fundamentals. That's needed because first nations communities need that hook, like every other community, in order to make sure that they know what level to target and what to do when those standards aren't met. It is just a fundamental way to give the same protections that the rest of the country has.