Maybe they are happy with the subscriber numbers as they are now. I logged on FFXI on a Saturday night I saw 3500 playing. I was like wow a lot of people still play FFXI and don't mind doing endless abyssea which is still packed.

In comparison FFXIV has around 250 during peak time.

If people are still playing with the game having little new content and lackluster updates like event items being added to porter mogs then it give SE little incentive to hire more people or put more people on FFXI. For whatever reason FFXI seems to have a really loyal customer base which is shown with 3000+ people on server during peak times.