Job design is the most lacking aspect of FFXIV for sure. Another part of the game that's lacking however are dungeons. I think there could be a way to give jobs more unique things to do primarily for dungeons and possibly alliance raids but certainly not savage raids or trials. Utility requires mechanics to enable them so only include those mechanics in non-competitive content and problem solved.

Or utility could be made more widely available like how we used to choose abilities to gain from other jobs, we could have a system like that but for utility. Make the abilities available to at least everyone in a specific role, then it's just a matter of deciding who does what. It's not as interesting as job-specific utility but it's a way to give players more varied things to do than run over here or run over there.