I think I want subjobs more than I want job balance.

[Ashgarth]

Really off the wall job combinations are the best part about subjobs for me, personally. When all jobs become the same, or there becomes a meta, everything becomes repetitive. There becomes one way to clear a dungeon, one way to play a job, one combo set or "rotation". That's so incredibly boring and predictable.

It's far more interesting to see variety. And subjobs lead for so many endless combinations of skillsets. I think I'd rather not be invited to parties by meta-minded gamers with little patience for things outside of established strategies than put up with dull repetition.
During the earlier days of Final Fantasy XI, I liked to play Ninja with Red Mage as a subjob. Was it effective? No, because it didn't get access to either the better White Mage or Black Mage spells. But I liked the fact that it made me feel like a Ninja Red Mage. Some people told me I wasn't useful for their party, so I missed some invites in Kazham. Or was told to go play a White Mage at times, rather than Red Mage. But in the end, I had fun despite those negative and discouraging experiences.

If XIV let me do similar, I'd probably like to try something like Samurai with Red Mage as a subjob. Using a katana and being able to cast Verraise would be awesome.

All those infinite posibilites end the moment the most efficient subjob combinations are discovered and it becomes the new meta. You can play it if you want to, but noone would want you, ever, in their teams.

Please let's not pretend you would get invites to a party in FFXI as a... I dunno, Dark Knight/Puppetmaster. It didnt happen no matter how fun you thought it would be.