Giving each job a second spec: would it work?

[Reynhart]

Do you imagine that having specs over jobs reduces the amount of balancing? If two specs on the same class/job have the same role, then one spec which performs better becomes the mandatory choice - this is the 'illusion of choice' problem. Furthermore if one spec of one job is better than everything else it becomes mandatory not just compared to other specs in the same job, but for the entire role. So they're going to have to end up using a lot of time balancing specs, and it's not clear to me why this would be significantly easier than balancing a whole new job.

See my previous answer. Most of the time, people won't have control over the party setup, so nothing will ever be mandatory.
Last time I checked, Relics were the absolute best weapons before expansion, yet, it was never mandatory.