Does it happen often ? Yes. Will it get better ? Sure. As soon as you reached level 50 and further contents, people will use their jobs better. (hopefully).

Until then, try to analyze their gameplay and explain it to them. If they do anything irresponsible or completely wrong, it's anyone who notices it's responsibility to tell. Whether they accept it or not is not your issue. You're the one who's gonna improve. If they aren't listening or willing to learn, who cares ? they're the one that are going to be terrible at their jobs.

For the record, Brayflox's last boss is a pain to heal as soon as the tank plays as if he's invincible and won't dodge, even when you are sync'ed. Your mana pool at this level is extremely low, and being forced to cureII and dispell doesn't help at all. I often have to tell the party "please move", or "please LB as early as you can, my mana is running low". As a sidenote, at this level Bards should have a skill (job 30) "Mage's ballad", aka "manasong", which you can ask for if you think you'll be lacking. That will regen your mana greatly, just make sure you stand by the bard (range is quite limited).

At level 38, you will get a skill, "Shroud of Saints" allowing to regen some MP for yourself. Be patient ^^