Point of order. The Declaration does not say abuses are necessary for independence. It merely lists them in an effort to justify what they were doing, but the Declaration says the right is inherent. This is the key sentence.
That to secure these rights, Governments are instituted among Men, deriving their just powers from the consent of the governed, — That whenever any Form of Government becomes destructive of these ends, it is the Right of the People to alter or to abolish it, and to institute new Government, laying its foundation on such principles and organizing its powers in such form, as to them shall seem most likely to effect their Safety and Happiness.
The key requirement for governmental legitimacy is "consent of the governed."
If a government no longer has that consent, the people have a right to abolish it. The reasons why the people no longer consent to it are irrelevant. What people consider Usurpations and Abuses are in the eyes of the beholder, meaning their own eyes.
So you constantly pretend, but in fact the Declaration from its first sentence is clear:
"Such has been the patient sufferance of these Colonies; and such is now the necessity which constrains them to alter their former Systems of Government..."
"We must, therefore, acquiesce in the necessity, which denounces our Separation, and hold them, as we hold the rest of mankind, Enemies in War, in Peace Friends."
So our Founders used that word "necessary" over and over again to explain why they did what they did.
Never did any Founder suggest disunion or secession "at pleasure".
But that's exactly what Deep South Fire Eaters did starting in December 1860.