the biggest thing I can't excuse is Gomu Gomu retcon, the prophecy and whatever, were supposed to be things Luffy just fit the bill to fulfill, because his dream overlaps with the idea.
The Savior because his ideals match the theme > the Savior because he was destined so
but no, Luffy is not coincidentally the savior, he is the chosen one, from day one, and it could not have been anyone else.
I don't mind the idea of Nika, itself, but Luffy should have been the next Nika figuratively, not literally be NIKA