I guess we all have to decide for ourselves what is sacred and what isn't. Some folks believe no factory gun should ever be modified, some are a little more forgiving, some believe nothing is sacred. That said, you can't really blame folks for modifying what were common, current production guns at the time. No more than you can blame one for modifying a brand new Ruger. We must also realize that we don't all have the same opinion, appreciation or uses for firearms. We must also understand that the men in question were not boutique firearms fanciers, they were the real deal. So in my opinion, anyone who arbitrarily dismisses their views or opinions because 80yrs ago they chopped the triggerguard off something they consider sacred has some seriously flawed logic.
That said, I don't see anyone cutting up a minty collector's piece. I see folks modifying a well-used and/or abused and usually refinished specimen. Besides all that, NO ONE has the right to tell another what to do with their own property. Even if I DO want to modify a minty collectible. It's my business and no one else's.