So imagine using as precedent a case that was never even defended against. So what were the precedents established?
1.The Second Amendment protects only the ownership of military-type weapons appropriate for use in an organized militia.
2.The "double barrel 12-gauge Stevens shotgun having a barrel less than 18 inches in length, bearing identification number 76230" was never used in any militia organization.
You missed the most important precedent. It's a subtle one, and most people miss it, but it is absolutely critical for understanding the current state of the US legal system.
By creating a ruling that directly contradicts the written text of the Bill of Rights the Supreme Court chose to put a major contradiction into US law.
For legal professionals to create contradictions in the law, or to be involved in writing or enforcing law that does this, is always unethical practice of law, without exception. Contradictions make the law harder for non-professionals to understand, and that creates a long term artificial demand for the services of legal professionals, hence the ethics issue.
Even the appearance of contradiction would have been a problem, and to make matters worse, the court ignored the well documented history behind the 2nd Amendment and ownership of arms in Colonial America.
It follows that the legal authority of the court in this case was actually limited to telling the government a constitutional amendment would be required before the law they had passed would be legal. That's inherent in the oaths the judges swear when they accept positions with the court.
Further, the right to ethical practice of law being one of the most important rights protected under the 9th Amendment (under any reasonable statement of such a right, even the appearance of conflict of interest must be avoided if alternatives exist), the judges not only violated their oaths to uphold the Bill of Rights, but by their example effectively gave carte blanche to the legal profession to ignore major ethics issues in the law. US law is now riddled with ethics problems, and while we can't blame all of that on Miller (Slavery, aside from the moral issues, was certainly ethically invalid, as were the Jim Crow laws), this case does serve as a very damaging precedent.
Worse, rights retained by the people under the 9th Amendment, by definition, can not be taken away by any entity of government. That's the whole point of having the Bill of Rights be open ended! This was such as fundamental issue (and so critical to overcoming the opposition of the Anti-Federalists) that James Madison actually put it in the document twice, in the 9th Amendment (rights retained by the people) and also in the 10th Amendment (which provides for unspecified rights reserved to the people). By ignoring the right to ethical practice of law, the court effectively created a second major contradiction in the law!
It's ironic, because less than a decade before the events at Nuremberg, the US legal hierarchy was effectively giving the US legal profession a precedent that would allow them to ignore the concept of individual responsibility with respect to major ethics issues, while claiming hierarchical absolution ("my superiors said it was ok"!), something that has largely remained true to this day.
This has certainly had a chilling effect on a wide variety of rights that can reasonably be asserted under the 9th Amendment, such as the right to privacy, but there are broader implications. Not only do we now live in the "Land of the Lawsuit", but there are all kinds of other problems in US federal, state, and local law that trace directly to the willingness of the legal profession -- following the example of the Supreme Court set here and in other cases -- to ignore major ethics issues.
It's not an accident that, for example, the federal tax code is 2700 pages long, a length and complexity far beyond any reasonable size, allowing a lot of loopholes to be hidden in the law, loopholes that lawyers and politicians get paid to write and implement. Similarly, many of the patent and copyright issues that come up here on Slashdot are complicated by legal ethics issues inherent to how these laws are written and implemented. Then there's the right to roam and the right to travel, both of which arise under the 9th Amendment but are often infringed in US law (even Britain finally recognized the right to roam, after a decades long civil rights movement). I could go on with lots of other examples, but a little research of prior Slashdot discussions will quickly bring these up. The net effect on the US legal system, and thus on society, is very bad.
Irregardless of where one stands on the right to bear arms question as it applies to today's world, the decision in the Miller case is one no rational person can stand behind. Those who believe the right to bear arms should be more strongly limited should focus their efforts and getting a new Constitutional Amendment. Anything else does tremendous harm to society.