Why did many states propose amendments or changes when ratifying the constitution?

Because The framers of the Constitution encouraged states to The framers of the Constitution encouraged states to provide suggestions for a bill of rights ...

Explanation:

The framers realized that as a country progressed, several changes might need to be made so the country could adapt and move forward. Not only that, different states in united states might face different difficulties/problem, which make it hard for them to create one constitution that fit for all people in the country,

Amendments were created not to discredit the original draft of the constitution. But as away to recognize that the country is imperfect and the government will have to constantly find ways to improve the condition.