I'm fine with caster raise, it's ok for some casters to have it and some to not, The question is the damage difference fair? No it should be much closer between all casters (BLM, Picto should be slightly higher for not having it, but it shouldn't be a massive trade off like current), raise is powerful but it's also situational. Removing or giving all casters a role action rez is just boring homogenization, we need less of that even if it comes at the cost of "balance" the best way of balancing it is tuning the numbers to be more fair and close and to not remove it Imo.

Mobility? Mainly a Summoner Issue, Summoners "phyical ranged" play style makes it pretty meta as a better red mage, Personally I'd add more casts per minute on summoner or let Red mage do more DPS then Summoner as it's clear that current summoner is always going to be the best choice as it's a phys ranged with better damage and rez, So summoner really needs adjustments, I will say RDM should have burst and melee not be apart of the same thing, so RDM isn't forced into melee to burst, Instead burst should be separate. Melee should be a slight gain.

Difficulty? No caster is Difficult at a base line value the Difficulty in BLM/RDM is optimising movements and knowing when to use movement tools around the fight, Again summoner would fit better and be more "difficult" if it had actual cast times.