So, I know that there are people who thinks BLU is a waste of resources, or that it should be a regular job, but if Blue Mages are bound to stay as they are nowadays, always one level tier behind, and with the limitations, how do you think they can be improved?
Not in any particular order of importance:
1) Weekly Log objectives: They need to be soloable, more as you can get credit for them alone, because currently you can't. We have Basic Instinct to attempt this, and a good solo challenge as it is harder than with 4 people. This would mitigate the bad party finder experience outside of job update times.
2) Aetherial Mimicry: This is such a crucial spell that need to exist outside of the regular blue magic repetoire and added as an innate job action learned early on. There's literally no choice behind picking it up (we have functional 23 slots), and at the end it can even be a newbie trap, since is easy for sprouts to miss it entirely.
3) Blue Mages added to the PVP roster: Jobs are essentially completely reworked for their PVP iteration, so there's no reason why not offer BLU enjoyers this option, and there's a lot of venues to explore, such as Aetherial Mimicry granting one of another job's action.
4) Updating early: I feel that x.2.5 would be a good time to give the update, since the first part of an expansion is usually lacking in content, but also to make it relevant for longer. For example, right now, is possible to farm some Endwalker FATE's up to Mare Lamentorum.