I would hardly lump all of those together, because obviously they have various levels of significance to our nation. The DOI has much to do with allocating duties or powers to the Federal Government, as it is the document, formulated to correspond with our independence, which articulated the principles behind our separating from Britain and having a Federal Government of our own in the first place. Neither the Gettysburg address nor any of Twain's novels can make any such claim. Without an independent nation, there would be no federal government. Therefore your argument that it has "no more to do with" allocating powers to the federal government is specious at best.
The rest of your argument, as is part of the court's, raises valid concerns but is unconvincing. Specifically, you mention attempts to modify the statute to specify the medicinally illegitimate use of a controlled substance to purposefully kill someone else. While you and the court acknowledge that the current Congress could not pass the amendment, it ignores the question of whether or not those who passed it felt, given the term "medicinally legitimate," was even necessary. You know as well as I that the courts have ruled pretty incomprehensively over the history of our nation, and has so often exceeded the powers granted it that it has become the norm rather than the exception. In this case, their ruling is inconsistent with itself. Only if it ruled against the constitutionality of the Controlled Substance Act could they legitimately claim that Oregon has the authority to determine what is medicinally legitimate. Instead, what happened is that the court has allowed the state to determine the meaning of a federal statute independent of anyone else. A federal statute without the means of interpreting and executing its provisions is not a federal statute at all.
Only one of the three branches of our federal government (the Executive Branch) has been attempting to use the CSA as a weapon to disrupt Oregon's assisted suicide law. Another of the three branches of our federal government (the Congress) has refused on two occasions to provide the Attorney General with specific authority to use the CSA as a weapon to disrupt Oregon's assisted suicide law. Now the third branch of our federal government (the Judicial Branch) has just ordered the Attorney General to stop attempting to use the CSA as a weapon to disrupt Oregon's assisted suicide law without first securing additional Congressional approval.
I think that it's time to recognize that, at the present time, this case involves more of a dispute between the three branches of the federal government than a dispute between the federal government and the state of Oregon. If Attorney General Ashcroft can either (a) secure additional specific authority from Congress or (b) convince an appellate court that he already has Congressional authority, then we might have the opportunity to concern ourselves with any remaining constitutional dispute that may exist between the federal government and the state of Oregon. But for now, we have a dispute within the three branches of our federal government and it is the other two branches of the federal government (and not the state of Oregon) that are frustrating Attorney General Ashcroft's efforts.