The fault I believe lies in two places. Both in the publisher and the readers.
Lets face it, humans tend to get bored with the same old thing all the time. If we're just seeing the same thing day in and out. It can be nice to see a sudden change. But anyone who has dealt with groups of people also knows that they are fickle as $%!@. They demand change, but then soon want back what they originally had.
Readers are also partly to blame for why nothing ever changes. It's because the readers wont allow things to change. Look at Superman. He's a broken and seriously overpowered character. You have to go to ridiculous lengths just to make a villain that's a credible threat. And once defeated, how to you then top that for the next story? Though, if you dare touch Superman's powers. The readers cry blasphemy. Many agree that he's too powerful, then wont accept any change. It's the reader fighting the idea of fixing what they know is broken. They cling to the past like a cat in water.
It's also the publisher's fault for feeding these tantrums. They are in a near constant state of change for the sake of change and not story. Then just as people are adjusting to change, the publisher changes everything back to the way it started. It always gives the impression to readers that change is pointless, because it's just going to be put back soon. Look also at the way DC published WONDER WOMAN, Remember in her last series where the comic was in the 30s then suddenly jumped to 600. That's a prime example. Who was that for?
It also doesn't help that when anyone tries to redesign costumes they go in utterly stupid directions. I didn't have a problem with the Wonder Woman pants costume. I had a problem with that ridiculous rolled up leather jacket. Someone needs to tell Jim Lee that went out in the 90s. Then we have the TV show costume that looked like a porno parody.
I personally like it when Wonder Woman's costume has themes of Greek design. It doesn't have to look like it's out of ancient Greece, but it could be based on something from the mythology.
The more reasonable thing to do is to have different designs for Wonder Woman that depend on the environment she's traveling to but has the same basic themes. If she's going somewhere cold, give her more coverage. When it's warmer, lean more toward tradition. Any reasonable warrior is going to know that you dress to your surroundings.
I agree with almost everything here other than Superman needing to be depowered for better storytelling. Would it help? Yes probably, but it's the same thing I thought when on the last Live Show a guest mentioned the impossibility of Trek doing another 100 year jump because they'd basically be gods eliminating any drama.
"Up your game son." If the Klingons and Romulans aren't cutting it (and hey Gene thought as much back in the 1st season of TNG a sentiment I agree with), stop trotting them out and find something new to challenge your intrepid heroes.
Toyman and Silver Banshee aren't cutting it? Then stop trying to send them out against the Man of Steel. Bring on some real threats. If that means 24/7 surveillance of Metropolis has to stop and Luthor will be free to work for months on end on his various schemes and innocent people die as Superman is saving some people elsewhere so much the better to challenge Superman with obstacles his prodigious powers cannot directly overcome.