I received a major revision recently. However, as I was making revisions, I realized that my first draft from a few months ago is badly organized and poorly written.
I want to make some changes to a part that the reviews did not complain about.
My advisor told me to only focus on the question raised by the reviews. And reminded me that making unrequested changes is very dangerous and can even bring up rejection. His point was that the parts of the manuscript that the reviewers did not raise questions about proved to have been satisfactory and accepted.
I personally agree with my mentor in general. However, without changing the original purpose, I hope to improve the quality of the article by better writing and expression, or even new experiments. Is it acceptable?