To begin with any class but your highest lvl gets a huge amount of bonus exp.
So Fates and dungeons which were already very good for lvling give even more exp now.
Then there is the chain grind parties which are even better with that bonus exp.
And the hunting logs for each class.

There might be a lack of quests, but those are mainly there to help the casuals get to the lvl cap at least once.

As you are already lvl 50 now it just shows that lvling is fast and does not need an increase to leave things to do for the long term.
Since you are lvl 50 you are already able to join all the content, so they are not holding you back.
It just allows everyone to get to 50 while the players with more time are able to lvl up more on the side.