The industry is full of this type of stuff, but it's more obvious when someone is playing with an archetype as an homage or when trying to do something new with an old concept. Astro City & Planetary being good examples. The base designs of the characters are all from existing concepts, but we know that's the point. Unless I'm mistaken, I don't think I have ever read an article with any of these guys explaining the same of their characters. Maybe Supreme, but I doubt it. Maybe they probably said something along the lines of yes, their characters are visually offering a tribute to established characters. I hope at least that much was said at some point. Otherwise, all that money was made off of ripped off concepts. And this is something the entire industry is guilty of at one point or the other. Are the X-Men just a rip off of the Doom Patrol? Are the Doom Patrol a rip off of the Fantastic Four? Messy business, we should probably just leave it and enjoy the stories we prefer to enjoy.
Advice I should probably take for myself, just as long as I don't have to hear about how creative these guys are and what artistic geniuses they must be. Kirkman, I'm sorry, but Liefeld is not the Kirby of our generation. Kirby is the Kirby of our generation, and he will be the Kirby of every generation because dammit, he's Jack Friggin' Kirby.