I like the idea of completely removing the party/alliance penalty for Capacity Points, even if there's still no reason to Exp in a group, at least this would provide an interesting balance, so that grouping would be better for this activity.
Considering how rediculous the grinds are for job points, people still won't be completing them any time soon even with a full alliance clear-cutting a zone.
I would also love to see Job points accruing naturally everywhere, like sparks, you said you're already addressing this, which is neat, I guess it would feel less annoying for it to be so painfully slow if you were collecting them everywhere.
Also, add some sort of repeatable RoE quest to rival "Deal 500+ damage" for support jobs to repeat while you're at it.