To me, WHAT was trimmed is much more important that HOW MUCH was trimmed.
I don't mind ALL the blank borders being trimmed so much (especially if the writing is unaffected), but I hate a dime-sized hole in someone's face, especially in their features.
And when you have significant or noticeable paper loss in the image, you are faced with a defect that will still be noticeable after the item is restored, OR the restorer will have to "dip the area in paint", which is not good for the poster, and likely will not age well.
Bruce