I think OP, but not only s/he, taken it wrong on the purpose to level all jobs to 50.

In first place, why do you want do that? When someone likes be an healer and doesn't like or find boring as hell do other roles, s/he does not need to play that roles, to keep just your only role is enough to do all the content (DoH excluded, of course).

If the reason is show to everyone else how much l33t you are with all maxed to 50, you also must be prepared to boredom and do things you don't like, that is something expected and really no one must be surprised, unless XIV is his/her first mmo ever.

I like to be an healer, and have anyway maxed all to 50, but for a precise reason on mind: I'd like know all the jobs, how they works, what are their good and bad points, and so on. First hand, not stuff read on the interwebb This makes me more prepared on MY job, on PvE when I know how some role must fight a battle, and ten thousands more on PvP, when I know what the job trying to get me down can and cannot do.

When you do other jobs, the world does not change, it is the world you left when you made the last main story. The thing that really changes is YOU! You will get new knowledge about other classes, you will learn when you have pugilists it is best your tank keep mob on its position and do not move it all times, and so on. It is your personal experience that changes. This is not a minor thing.

When you're done with your main class, you cannot expect so much from a world you already have explored at large, you main focus will become to learn how other classes works, and try to get out the best from them.