As the content ages, getting full Blue Mage parties together will become exponentially more difficult which should probably see some form of nerf to do as the OP says and not restrict skill learning for players catching up to future content releases. I would say that skills should be guaranteed to drop, even undersized, as long as the party is only BLU mages to relax the full party restriction and allow people to catch up.

For the Blue Mage Log and Morbol achievements, I wouldn't relax this at all since they are designed to be extra challenges to complete for fun.


As for BLU abilities, I wouldn't make any changes to how they are now. A full party of Blue Mages can do things that a party of traditional jobs cannot while also being limited in what they can do in each role. That's what makes Blue Mage unique and as long as the fights that teams of Blue Mages can queue for can be completed with the skills available to them, then there's no need to change anything.