Merging two systems and converting all the data is a pain. Then there are all the links with the reservation systems and partners.
I guess the sensible thing to do is for them to offer a manual merge option for people who feel they can benefit from the merge. Basically, just add up the segments/miles from the tally, change the status manually on both systems and maybe even transfer all the miles and close one account. I doubt this would impact a boatload of people.
I am actually one of the few who are benefitting from the delay

Made gold on the Guest program last year but only silver based on the entire year's count.
Does anyone know when they will stop using SABRE and move everything to SHARES on the reservation side? On the FFP side, whose system will they use?