This is just speculation, but Chicago was greatly influenced by the Genovese crime family. They could have influenced him to want to use the traditional ceremony. Ricca died around the time that Aiuppa became boss and was going senile before that, according to some people who knew him. Maybe he was the one who wanted to maintain the informal version and with him out of the picture there was no one to prevent Aiuppa from doing it his way. Accardo, who like Aiuppa had Sicilian parents, probably didn't care either way but surely gave his approval. That's my best guess for now, but maybe someone else has a better one.
I know very little about the "making" ceremony, but you did mention something that interests me. Do you know an approximate time when Ricca started having Senility problems? I have documentation that he was most definitely having problems by 1967. What I don' know is if he was having problems earlier, maybe 66, 65, 64.
If he was in fact having problems earlier, that might explain why Accardo stepped-up and took a more active role by "bearding" for Ricca. Just speculation on my part.
I know this is off-topic, but I just wondered if you had a time frame relative to Ricca's health problems. Thanks