Here's Crawley ,Amateur Photographer,March30 2002:
"In the 1950's, researchers found that although fine grained negatives could give higher resolving power,the overall sharpness and detail crispness of an image is better from a rather grainier negative.The reason is simply that the grainier negative image diffused less in the enlarger,so detail was crisp and main subject outlines sharper"
"The point was made that,subjectively,the enhanced overall impact of a sharp print image makes any increased grain insignificant-especially when viewed from a normal distance rather than close up with a magnifying glass".

Of course Beutler started this many years earlier,he wrote a book in German Meine Dunkelkammer Praxis (sp?), I never saw it.