The early issues of Action will have Superman in the "Hobo With A Cape" costume. I know, it still sucks.
I think I know what he is going for with that, it's a punk rock thing.
See, punk performers wanted to break down the invisible barrier between audience and performer, where before the audience would look upon the artist as some kind of demi-god, like Hendrix, Morrison, etc, the punks wanted to make it look as if anyone could get up on stage, and in turn, they could step off stage and blend into the audience.
So, Superman could be doing something like that in his early days, wanting to appear as one of the people, dressing modestly, instead of showing up on day one in a bright shining suit that looks like it was stitched up on another planet. He wants to show people that although he has powers, underneath that, he is just like them.
and then when he has ingrained himself in the culture, and earned the trust of the people, he whips out the skintight future fashion, and people appreciate the fact he has now become a symbol, and needs the appropriate uniform to go with that notion.
Because, I guess you could think, him showing up day one in that kind of uniform would be assuming he was already a symbol, whereas his actions have to earn that staus, same as being a recognised as a protector of the people, he has to earn his uniform, so he can wear that proudly in public, without seeming pretentious.