Most agencies that promulgate regulations have internal courts to resolve disputes between parties. These are not judicial courts (in Federal parlance, Article III courts) and their decisions have no precedential value, only being binding on the parties themselves. This tends to surprise students unfamiliar with Administrative bureaucracies but the reason is quite simple and practical: if Administrative Courts had precedential weight, their decisions would interfere with their Agency's ability to promulgate new rules or shift policy based on the directives the President or Governor. In the Judicial Courts, precedent exists to promote continuity, but that is somewhat against the mission of the Administrative State.
That being said, Administrative Court decisions are on the periphery for research and you likely won't come into many situations where you need to access them. However, they are often a decent window into an Agency's activity in the near future: they will often deal with novel or unexpected problems and the opinions they write can signal a new rule on the horizon. With that said, decisions older than about a year are typically not useful for a substantive purpose, as if they presaged a new rule the process would have started by now.
An important detail specific to Michigan is that the "court decisions" coming from the Attorney General's office - AG Opinions - reflect binding directives for the State Government. They are not merely advisory. This is because, unlike in the Federal Government and many states, the Attorney General is an independent, democratically elected office that does not necessarily serve the Governor.