No, again, you've got it exactly backwards. "Solid precedent" can now be established via the development of jurisprudence under stare decisis, as is the judiciary's role.

Under Chevron, agencies themselves were interpreting and re-interpreting statute law as they saw fit, and there was no binding precedent at all.

You're literally staring at the courts dismantling several decades long precedent, though?

Yes, sometimes that's necessary when bad rulings slip through. If there was no mechanism to reverse bad precedent, we'd be in a pretty bad situation -- we wouldn't have this ruling, we wouldn't have Brown v. Board of Education, etc.

But the courts do this carefully and infrequently, and create a level of stability in the law that's far stronger than allowing the ever-changing landscape of statutory law and administrative rule-making to provide the final say over complex questions.

That's exactly the point of this ruling -- the courts had delegated the responsibility for shaping jurisprudence that defined the limits of administrative power to the administrative agencies themselves, allowing those agencies to interpret and re-interpret the boundaries of their own authority in pursuit of whatever ephemeral issue they were focused on at the moment.

This was an abdication of the courts' own duty, and it's a very good thing that they've decided to take responsibility for it once more.