I would like to tell you that BLM is the reason I'm still playing this game and I love the design, even more so now that we got a lot of movement skills during 60-70.
I tried other jobs and don't feel so natural like BLM. You get insane DPS when you can stand still and cast (and by insane I mean I've nearly never seen anyone not BLM doing more DPS than me, not counting raid contribution of course).

Before 60 yes it's quite hard to move without losing DPS, but at 70, you have
Triplecast: Let you freely move for ~7s every 60s
Swiftcast: Let you freely move for ~2s every 60s
These two alone let you move 1/6 of the time already.

Then you also have
Thunder proc: freely move for ~2s.
Fire3 proc: freely move for ~2s.
Fire3/Bliz3 change phase: freely move for ~1s enough to get out of most AoEs.
Aetherial Manipulation: freely move to your friend (I found that at least one will be out of AoE).

Regarding learning the fight: I find out that it's only required for EX Primals and Savage fights (which you do while learning the mechanics anyway so it doesn't feel like more problems than any other classes). For other dungeons, just improvising BLM kits is totally fine and you don't really need to absorb any AoEs either.

My advice is like the others. Get him to 70 and play for a while, if you like him you'll like him.
If not then maybe BLM is not the class for you and you can try some other classes. No every class is for everyone I guess (like how I can't get myself to love melee classes XD)