For a lot of the jobs the classes become pretty much obsolete when you get them, even for solo. As for the LNC/DRG example I think that's more of an issue with class balance around that battle than job mechanics. All things considered it really is the worst fit for that fight.
I hadn't really considered the PvP aspect of classes, to be honest, largely in part because I haven't really touched them since 1.21. That'll be really interesting to see how it plays out whenever it's patched in.
