So we are finally getting somewhere. I would describe BLU as "performing old content in a new way", but you likening it to a challenge run isn't invalid. What you have told me is that BLU isn't your sort of content, which is absolutely fine, but it doesn't make BLU a waste of time or resources. You just identified my exact stance with PVP, its just not for me. Why is PVP or crafting fine but BLU isn't? Just because you really like BLU in another game? I'll repeat my argument, CHM is my favourite job of all time, and the devs have the right to implement CHM as ALC, same as they have the right to implement DRK as a tank despite someone on the forums whose all time favourite job is DRK hating the playstyle of tanks.
I would actually like you to address my point on constructive critisism, I would genuinely like to know an informed opinion on why BLU is a waste of resources that doesn't boil down to "I can't do 80 content with it", because that's not what it is designed to be, I can't raid with my ALC either. Once we have that reasoning, we can start asking the devs to improve BLU, and BST if they decide to implement it as a limited job. You can ask me my complaints about BLU too, I have many, the most vocal of which I have been is the branding of "limited job", I hate it.
There are other jobs far more deserving of these concepts, Rune Fencer and Geomancer being prime candidates. Forcing BLU into these roles over these two would be a strange direction to go.