If the system is fun and not a throwaway then yeah.
But it has a risk of being just a sightseeing log with RNG-based grind which would be a let down to say the least.
Plus there's a lot of people that wanted to main BLU and wouldn't be able to do it. I am fine with BLU being limited just because I haven't had any intention of maining it, but as a side activity it looks interesting to me. But I'd prefer BLU to be a vaid option for people that wanted to BLU.

To be honest, I don't buy the balancing issue to be the reason to not make it a real job. Yes learning 49 and then some skills from monsters is unique and fun and it could still be that, BLU can have it's own side activity just like BRD has perform. No one expects a BRD to use perform in raids. So BLU could use learning to get their skills to use in a solo content just like it's going to, burt also have its regular skill set for group content.

I bet we're going to see a patch called "Unlimited Blue" or some such later down the line, that will make BLU a regular job. Optimist in me says that limits are there to be broken (heh), and they might work on a core skill set for a BLU according to popularity, usefullness, power etc. of skills used by people doing their BLU content.

I do believe that BLU deserves to have both places in the game, both a side activity collecting fun and a place in group content. Might never happen of course.