I suppose a more complete descriptive label for the USoA is a "Federated Constitutional Republic".
True, the new (in 1789) central body of the federal government (in contrast with the Confederation or Confederated government created by the prior charter document) was more powerful than the Continental Congress.
By 1791 the new charter had been amended to preserve sovereignty of the States. I force myself to think of the states as fictitious entities, just like a corporation. Recently I saw a headline on Freedom's Phoenix which reported that at least one, possible two maybe, states passed resolutions declaring that corporations were not people. States aren't people either.
People are real. People have rights.
In a republic, the people are the (only real) source of power. They make that Lockean bargain wherein they surrender a few rights for the protection of the rest.
The 10th amendment is a division of labor statement. It divides tasks among the central body of the federated constitutional republic, the state bodies of the federated constitutional republic and the human bodies (individuals) of the federated constitutional republic.
In conjunction with the 9th amendment, the bill of rights is a very strong people-power document. It strengthens considerably the statements regarding the republican (not to be confused with the major political party with a similar sounding name) system of government in the original 7 articles.
Natleson paraphrased "rights" as "exceptions to power". If you can have "unenumerated exceptions to power", you can't have unenumerated powers in the same document.
Yet Hamilton used a phrase "implied powers" in support of establishment of a national bank.
That being so, it became convenient very early on for some to ignore the constitution. Doing so is not a recent development.
I doubt whether another amendment related to State powers will fare any better than the 10th amendment.