Scenario: You've written and re-written and polished your book. You've got feedback. You've re-written and re-polished. You've sent the manuscript out. An agent likes it but makes suggestions for rewriting the manuscript - do you do them? Alternatively, the agent has taken the manuscript on and sent it out, an editor at a publishing company is interested but wants changes to the manuscript - do you do them?
In other words, do you make changes BEFORE anyone commits to your work? It's not unusual for people to do extensive re-writes and still get turned down.
I think Yes - if you really really understand the underlying reasons why they want the changes AND agree with them.
For example, my Dutch editor said she wouldn't buy Nice Girls Do unless I made a story change. She said that readers wouldn't believe that Anna would end up with Will because they hadn't already slept together. She didn't care how I got them into bed together, only that sex had happened and that it was great. I understood the reasoning, and agreed with her. I made the changes - which meant whole chunks of new writing, not just tinkering - and liked the end result so much that that version is the one that was published around the world, not just in Holland.
So I understood the problem, agreed with it, and could see how I could change the ms to accommodate a solution which strengthened the novel. The understanding is key.
The problems occur when the agent or editor says something vague, like they want the character to be a little more positive. You look at the ms, think your character is already pretty positive, but add a few more positive bits of dialogue. In other words, you're showing willing with the idea of changing material but without really understanding what the underlying problem is. Because you haven't understood, you can't deal with the problem - it'll be luck not skill if you get it right.
If you don't understand, ask. If you can't ask, then talk with writing friends - can they see what the agent or editor is getting at? If you understand but disagree, again try to get a discussion going. Put your side, listen to theirs. It there a third way that will satisfy both of you? I've re-written drafts and my editor has been surprised at the extent of the rewriting, but it's been the only way for both of us to be happy - and I assume the readership too, as the rewrites have always been better than the original.
Try to get a discussion going and keep at it until you can see the way forward that works for you because if you try to write without your heart being entirely behind what you're writing, you will fail.
And then what? Which version is better? I've seen people re-write extensively and still be turned down. Then they send out the revised ms, and get more suggestions that lead back to the first version. That gets turned down too. The author is left confused, demoralised and derailed. Now they have three versions, and they have no idea which is best. Or even which is closest to their original vision.
So the answer to the original question in my opinion is simple - Yes, if you understand, and No if you don't.