So? I don't really see what the problem is with that.
Reality is we still don't know very much about Roger. Everything we know is still quite superficial and yes what we know strongly resembles Luffy, however Oda wrote it in such a way that this isn't just Roger-Luffy, but a group of people namely the 'D'. Whitebeard even specifically said Roger himself was waiting for certain people.
Also till know I didn't really get the impression that Roger is such a goofball a Luffy. Even though they look similar, Roger always appeared to me like a clever man. Even when he would do outrageous, insane stuff, he comes over like there is still a calculating mind behind. With Luffy there is no calculation, it's almost like his head is empty. I mean it has been pointed out a few times by now in the manga that, without his nakama, his ship would probably sink in a flash. Not to mention Roger, even though they even look similar, appears like a wild man that's mad, happy and just crazy at the same time all the time, while Luffy just appears like a happy goofball.
I mean in Naruto everyone could see from miles away that Naruto was the son of Minato and then seeing Roger and Luffy you expect there is some kind of a connection (even if the times don't match). Then suddenly he's the son of the worlds biggest criminal, Ace is his foster brother and then Ace is Roger's son! (still pissed at the person who ruined this for me as I wasn't at that chapter yet).
I don't even see a connection between Zoro and Rayleigh other than that both of them have a vertical scar over their left eye. Both personality and appearance wise they barely resemble each other.
Yes there are some parallels, but overall they are still very different. Oda makes Luffy appear as the same type of person as Roger, but he isn't Roger, he is definitely Luffy.
