they gain power and relevance when printed large.
Without some meaningful qualifiers, that statement would apply to any photograph, no? The corollary is that photographs
lose relevance and power when printed small. If such criteria were established norms, you'd find them in judging standards, and art critiques, and by now all artists would be making the largest prints possible within their means. A kind of arms race.
I don't at all argue that large prints are popular, sell for more money, make marvelous wall decor, and may yield lots of "OMGs" when viewed whether or not there is any photographic merit aside from size. But I can't yet see an
intrinsic property of size as a qualitative measure. If size was such a quality measure, there would be subjective and possibly objective formula for determining the
optimum size for any photograph. Should "Migrant Mother", shot on 4 x 5, be displayed as a 40' x 50' print to communicate the power of the photograph, or is size irrelevant to the power?
I also yield, of course, to personal subjective preference. "I dig massive photographs," is a routine expression of subjective preference. But, "massive photographs are
better" needs a rigorous rationale.