As I've mentioned in the past, that's due to limitations from turn-based combat. Turn-based combat doesn't have much room for hybrids to shine without making the player waste turns and lacks opportunity via mechanics. You're not getting procs and you're certainly not getting the ability to combine aspects of your class into something more. I mean, if you look at how RDM was designed in the console FFs, its elements are all segregated. Mediocre melee, mediocre white magic, mediocre black magic. Which is why some of the FFs had to make up gimmicks like Doublecast to make it not be a waste of code.
Once you throw turn-based combat out the window, a world of opportunities opens up, because then you can do things like procs from melee attacks that make your next spell instant, melee + magic combos that leave a lingering enchant on your weapon, the ability to charge your weapon with magic energy and then release it as a powerful spell, having melee strikes weaken the target to make them take more damage from your spells, and outright being able to enchant your sword (which FFXI did). All of these involve an actual marriage of spell and sword to work. Hence why MMOs depict hybrids differently, especially after they realized they could stop bait-and-switching players into picking them up.
My issue is more that it's a ranged caster that makes very little use of the sword. That's why I compare it to the Revelation Swordmage. As I've said before, you could remove the Cross Cut => Chant du Cygne => Millionstab combo and replace it with Ultima and you'd see no difference in the gameplay. That's how tacked on the use of the sword is. If they wanted to make a mage that balances white and dark magic, I say go ahead; Sage and Magus are available for that. Just don't slap a red hat and sword on them and try to call them Red Mages.But really in a game with such a clear distinction between healers and dps there's not much they could have done to support both on one class.