I did the original "navigation strip" which is up on rp_tutorials and is all over games now. It's really neat to see it used everywhere, but really? It was super insanely basic coding, it was just that I was the first to use that basic HTML that way. I see no reason to demand people credit for it, as it's so simple, so basic, makes games all around so much easier to navigate. Honestly I think it became as commonly used as it is because I didn't ask people to credit... it just became viral. Cool to see my little thumbprint on RP.
I suppose I'm different from a lot of those who RP, though. I always credit those I take icons from, but I don't ask people to credit icons I've made unless I actually hand drew them... which I did do for one fandom game. But really, I didn't take the photos or draw the comics which I'm making icons from, all I did was crop and re-size. I'm not crediting the original photographer/artist, so what right do I have to demand other people credit me? I just don't get that logic.
All that said, if you do want credit on icons/layouts/etc, that's fine, but I think most people need to do, just as you said... be a little more respectful/polite. People are often in Vents complaining about how they got called such-and-such for stealing an icon when they just cropped the same photo as someone else in a similar way. Being polite and triple checking that they are completely identical before raising a complaint is the best way to go about things, IMO.