The main thesis of this comes at the end. To paraphrase, "If you open a book that has good writers and talented artists, there's a chance you may be reading the best comic ever."
So yeah in the end, it doesn't matter a whit. When a new writer or even editor comes on board a title that has been going for years, the tone is going to change based on the direction they want to take. Levitz taking the reins in the early 80s is a great example, as is DnA in the reboot.
I think the issue becomes when the characters are altered to such a degree they become almost unrecognizable from what they were before. Which may or may not coincide with the quality of writing