Isn't the problem with lifetime gold (or silver) that once people earn it they might decide to switch to another aliance to try and get status with them as well?
I am currently loyal to BA and working my way up the status with BAEC helps drive that, but once they gave me a lifetime gold card, I would feel set-free to book with the most convinient or best value airline without any longer worrying about tier points etc. It would be liberating!