I really love Red Mage, it became my new main immedietly.
However, its true that i was actually pretty dissapointed to find out just how easy this Job was ,as i thought it would be more complex with 2 different bars.
The Sword combo is nice but you use it not so often inbetween spellcasting.
While i dont mind the current playstyle much, i also wouldnt mind using the sword combo a bit more often but maybe since this is a new class SE will change something.
One could think about lowering the cost a bit or raising the generated mana to use the sword combo more often.

I was able to help alot in some new dungeons by raising the healer and heal the tank until the healer was recovered, that felt nice.
To make this playstyle a bit different you could also give the Spells an extra Effect depending on which mana is higher and maybe adding a bit to his "support style", like if you use verearo while white mana is higher the enemy gets an effect so that the targeted player gets hp for each attack,(like Bloodbath) and if you use it while black mana is higher, i dunno something different.
That way you would give the RDM more options and the player a bit more to manage.
They also could give the Melee combo a different effect depending on which mana is higher.

Though, as i said i love the class anyway.