it would be nice if leveling was less exploitable

[Penthea]

Doesn't "jack of all trades" mean "pretty good at everything"?

Maybe I'm still missing the most important spells, but right now it looks like BLU is just a terrible dps, a terrible tank and a underwhelming healer. Frankly, it cannot even be compared to other jobs because of how underpowered it is.

It can actually far outpace standard dps classes in pure damage on trash, but on bosses it is often lacking. White Wind can be crazy strong as it heals equal to your own hp, but the flip side is that can also mean it's very weak. The lack of a res and a low cd cleanse can be an issue. I found it okay as a tank in 4 man content, but I suspect it won't be very good in hm and ex trials.

I personally found with blu that the skill and experience of the player has some serious impact on the class. There is no rotation. There is no fixed way to play it. I have met some blus who thought spamming 1k needles would get them through everything (spoiler: it doesn't) and they forced the rest of the party to work a lot harder, and I met other blus who were prepared to use any spell if the appropriate situation arose and they were a dream to play with. The difference between these two kinds of players is astounding at high lvl.

With that being said there are some serious holes in blu, even when you consider it's a jack of all trades class. But this could very well be due to the current low lvl cap. It could be a very different story when you can get it to 60 or 70.

Its sole reason of existence is the masked carnival, using it for anything else is just a waste of time. It might be fun if you're doing it with friends while chatting on discord, but what isn't?

I'm not going to tell you that you're wrong because liking something is a matter of opinion. I have had great fun doing The Masked Carnivale on my own. I find blu itself to be a nice change of pace from the rest of the game.

Also, lvl 70 players carring BLUs in instanced content to help them learn their spells gotta be one of the most absurd things I've ever witnessed in a videogame. I really hope this wasn't their intention from the beginning, because it's just bad design.

This one is somewhat a matter of choice. You don't need to have lvl 70 players to help you, but the other side of it is it can be very difficult to get help from someone who isn't lvl 70, given that's the current max lvl. The lack of lvl sync when you do instances as blu is very annoying. It would be great if you could get help from your lvl 70 buddies, but when you're in the instance you have the choice of all being lvl 50. Not everyone enjoys getting boosted and it sucks that right now this is the only option for most players who want skills from some lvl 50 content.