I'll preface this by saying I have been waiting since 1.0 for BLU to be a thing. I haven't put a ton of time into FFXIV (though my sub has been going the whole time in anticipation of BLU) because none of the other jobs click with me.

Their reasoning for BLU to be limited is a really big cop out. We have a ton of watered down classes.

Summoner. Summoners throughout the Final Fantasy franchise have been extremely powerful beings. Summoning things like Atmos and Alexander that can destroy cities or even countries. Yet the Summoner we have now doesn't even summon full Primals. Hell they don't even have access to even half of the Primals/Summons that have existed throughout the FF franchise. Yet it is okay for them to be watered down to fit into FFXIV and not be to OP.

Black Mage. Black Mages have also been extremely powerful throughout the Final Fantasy franchise. We don't see every spell Black Mages have had in the FF franchise accessible. Death is a Black Mage spell and it wasn't even level 5. Just Death. Meteor was a Black Mage specific spell, not a Limit Break like we have. Not to mention Comet, Break, Demi, Ultima, Apocalypse etc.

Red Mage. Also another watered down version of the single player games. Red Mages don't have access to their full repertoire for sure. They don't have all the healing spells they have access to throughout the single player games, they don't have spells like Toad and Mini. Or Raze which was another spell that caused Death.

So BLU could have been made in line with all the other jobs that were watered down to fit into FFXIV and still be enjoyed by the player base that wanted to main BLU and have been waiting for it for a long time. For whatever reason though they seem to have it in for BLU.