Jason, it seems to me that getting an open does not just mean changing the maintenance practices, growing rough, narrowing fairways and grooming the greens fast. They don't call Rees "the open Dr" for nothing. Pretty much every open course has yielded to design changes, many related to lengthening, relocating and reshaping bunkers, etc.
While some might say the architectural design work on various old classic courses has been to improve them, (perhaps your RTJsr Hazeltine there in TCs), I think it is at least debatable that changes over the years to open hosting courses have yielded more interesting golf courses for the members once the open show leaves town. Not to mention, alteration to original intent of what the course was to play like, by the original archie.