The thing about the muted colors is, I guess, to make him more subtle, less standing out. But if he wear supposed to be subtle, he wouldn't wear a costume at all, would he? He'd just wear street clothes, like Clark did in the first eight seasons of SV (and all the characters on that other show by Tim Kring).
Why doesn't he wear street clothes, why the costume? Because he has to stand out. He wants people to trust him, which is why he doesn't wear a mask, and people in a dangerous situation have to immediately recognize him as Superman, the one who can save them. He has to stand out, and that's why muted colors just don't work for him, in my humble opinion.
That's not strong logic, much less an persuasive argument.
First, it's an assumption rather than fact that the intent here is to make him stand out less in a crowd. In that get-up, especially with the huge red cape, there's no place that he's not going to stand out just fine. Secondly, anyone who makes his entrance by flying in through the window has everyone's attention, I can guarantee you that.
If the rationale were that he has to stand out to the maximum degree possible - well, he'd stand out even better if the costume were day-glo and phosphorescent at night. It's not, and the only reason this version seems less eye-catching than the old comic book one is by comparison with what's familiar.
Aside from the fact that the rationale that "he's wearing the outfit to stand out' doesn't make that much sense, it's not a given that this
is the reason for it. If that explanation has been offered at some point in the comics -well, so have alternative explanations in different eras. One of the earlier ones was simply that Supes needed an indestructible outfit, and the only material that fit the bill were the red, yellow and blue blankets from his Kryptonian rocket. He was therefore stuck with the garish costume scheme. Apparently the current explanation is that the design of the tights, armor or what-have-you is itself Kryptonian.
All such explanations are reasoning backward from the fact that the character was established as dressing this way for no particular reason. If you were used to seeing him dress in black and silver you'd have accepted the offered explanations for that as given and would be startled by the introduction of bright colors in a movie.