I thought the whole thing with Mr. Eko was pointless and was done as a way to insulate against charges or racism. Same thing with Ana Lucia. It's not that I didn't like Eko as a character. It's just I had a hard time understanding his relevancy to the plot. (They still have never explained why an African drug runner/priest was on an airplane going from Australia to Los Angeles) The real problem with Michael and Walt was that Walt's actor went through puberty, making it really difficult to fit him into the script when he was no longer this cute little boy in a story that is only supposed to be covering three months on the island.
I do know that, if realism has anything to do with it, there's not a shred of Jin underneath that tombstone back in Korea.