What was said in the Live Letter, now that it has been officially translated:

We’re planning to set the loot rule for all alliance raids to “Greed Only” starting in Patch 4.3. We originally intended the alliance raid rewards to be a means for players to obtain gear for their secondary jobs; however, it is difficult for players to participate on these other jobs while wearing lower item level gear. This leads to many simply having to go as their main jobs which makes them unable to hit Need on the items they really wanted, resulting in needing to run the content multiple times. To resolve this issue, we have decided to limit the loot rule to “Greed Only,” making it possible for players to join as their main jobs, while being able to obtain gear for their secondary jobs.