Now I've never played a Paladin, but I do remember that Blizzard has always struggled with getting a resource system to work for Rets.
Part of the problem was always that Rets had a very small mana-pool, due to stacking mostly melee plate stats. This was fixed during BC for most extent. Still, spiritual attunement also contributed to Rets difficulties by making them have endless mana when taking damage, but suffering when not.
Now I realize that Judgment of the Wise plays a part in replenishing a Rets mana. But I'm sure there must be more to it.
Otherwise I'd imagine building a rotation for Ret wouldn't be such a struggle. Just have a low damage, short cooldown ability that restores mana, and have a few heavy hitters that cost mana. Voila, you have resource management.
But afaik, in the current state of the game, Ret might as well not have a mana-bar, except when healing. So what's the real problem with making Rets mana-management meaningful?