i think one solution for this would be quite a simple one. se has dropped the ball and led its entire playerbase into the belief that a single character can have any and as many job/classes they like and won't be punished for this. as it stands we are punished and locked out of content for no good reason really.
there could be a potion similar to a fantasia that allows me to split my character jobs on to a different character permanently instead of it being on one character that is essentialy gimped and locked out from content except for the one class that is the main. this way we could do the content more and gain more actual value from the sub.

are people still going to scream overflow of loot and unbalance in the world? this is essentialy the same as rolling multiple different characters.