SE can design classes and jobs to have compelling kits and story lines independent of changing (or not) how level sync works. I have my own hot take on class/job design in another comment.

Designing classes and jobs such that they have coherent, fleshed out kits at Lv. 30, 50, 60, etc. goes a long way towards solving any issues with level sync, even without changing how level sync itself works.

The reverse does not. For example, right now, syncing a Lv.87 WHM running Lv.53 Sohm Al up to Lv.60 still results in a garbage-feeling kit because Afflatus Misery is all the way up at Lv.74 and Afflatus Rapture is all the way up at Lv.76.