That's the problem though. What's "good" changes based on people's experiences. What wasn't good in 1913 - wasn't good in 1913. If it is good now, it's only because now we have experienced things which have changed how we perceive things to be good.
There is no such thing as inherent good. Good is always subjective. A boat is good for crossing water. A boat is bad for crossing a mountain. So is a boat a good thing or a bad thing? Depends on the circumstances. Though one could argue that a boat is objectively good for crossing water, it is also objectively bad for crossing a mountain. So it is still not inherently good, even if objectively good or bad depending on context.
Art I think is much the same way. It's just art. Whether it's good, or whether it's bad depends on the circumstances. Sometimes what was good decades ago isn't good today. Sometimes something that just confused or bored people decades ago, is today very interesting and good. It doesn't become good retroactively, because people's ideas of what was good were different long ago, and we don't have time machines to go back and convince them otherwise. 🙂
And there is certainly plenty of things that were created then that are art and do stand the test of time. Steichen, Stieglitz, Brandt are just a few that come to mind.
But to your point the bar does move as it should but the fact some of the same elements that go into making an objective decision on what is good and whats not (which should also not be confused with what is or isn't art) we do have 2000 plus years of helping determine what is good and whats not.
A great photographer once told me all the visual elements in the frame like lines, tone, shape, form, etc are either helping your visual statement and if they are not helping then they are fighting or hurting that statement. And all of those things can be helping and making it a good photograph and it still might not be art.
Most of what that is created is not art. That doesn't mean its a bad painting or a bad photograph its just not art.
......"most of photography is not intended as art and should not be judges as such."
-Ansel Adams
"Art for art’s sake is dead, if it ever lived."
- Edward Steichen
"What is the art experience about? Really, I'm not interested in making "Art" at all. I never, ever, think about it. To say the word "Art", it's almost like a curse on art."
-Joel Meyerowitz
I think we should just create and not worry about art. Strive to make good photographs. Ones that are deeper than just, as Weston called it, the obvious or nouns. I am talking about personal work here because most commercial work needs to be the obvious or nouns.