I guess what I'm looking for is how this all relates back to the Raise issue.

Raise influences party composition in raid content. However, changing party composition does not resolve the issue. If you have the option of access to more Raises, you'll take the extra Raise Jobs in just to see more of the fight. If the enrage is tight, then you'll just swap them out for damage casters. The only difference that two caster slots would achieve is that your mandatory SMN and RDM would each be forced to play and swap out to BLM and PIC (and agree in advance on how that would be divided up). As it stands, you just need to know one of SMN/RDM and BLM/PIC, with the choice being yours of which two you want to learn.

If you want to give players choice around what jobs they bring, then there need to be limits placed on Raise uses per fight. You also need to make Raise ubiquitous, such that you don't have to bring a specific job to access it. Again, I don't think we'll see any solutions this expansion, but I think the long term move will be to have a general 'Phoenix Down' action with a recast/use limit that removes the need for a 'Raise Job' slot.