The problem is that people rarely come back - a small percentage of people will reactivate in a game if they have decided to stop playing and fixing any issue other than low server populations will frankly not fix the bleeding. They need to work to keep the current population happy and people not being able to experience any multi-player content will just end up leaving.
Plus, relatively speaking, it's not a challenging, technical task - just requires some up-front thinking about potential issues and then use the existing tech to perform the actual transfers/merges (which they obviously have since they allowed oceanic transfers)
However, I do agree with your line of thinking