For atheists, aren't they supposed to end up on the godplane that closest matches their philosophy? Also, it's kinda hard being an atheist in a setting where gods verifiably exist. Agnostic, probably. But actual denial of the existence of deities is a bit of a stretch.
It's not
atheists, technically, who go to the Wall of the Faithless, it's people who haven't pledged themselves to and dutifully worshiped a god in their lives. So apatheists, atheists and agnostics alike get to experience the joy of having their soul ground to nothingness over thousands of years to serve as an example to the rest.
If they
did pledge themselves to a god, but didn't follow through with corresponding sincerity of faith, they're called False and instead have to pull a few thousand years of guard duty in the City of Judgment, fighting off planar invaders, liberators of souls or other troublemakers in the domain of the god of death. All within sight of the aforementioned Wall of the Faithless, mind you, so as to get a good sense of what they barely lucked out of.
On reflection, if the size of the Wall and the army required to man it is any indication, it's probably much easier to land your apathetic ass in either of them than a flippant assessment of the prerequisites would indicate.
Not that any of this is necessarily canon at this point what with edition change cosmology bullshit, but it's such a neato piece of lore overall that it'd be a shame to not include it in a setting that includes the Fugue Plane and the City of Judgment.
EDIT: on the topic of healing magic, Neverwinter Nights 1 and 2 both had instances where if you had healing magic, you could help somebody overcome their wounds much faster. They'd usually be pretty chuffed about it, too. Usually at the start of the game, though (you know, before crunch time when designers can afford to put in nice touches that feel cool into their overall area design).
Final Fantasy V also had a pretty cool scene where the party tries and fails to use a Fenix Down on a guy after he got super-rekt in a fight.
There's also an issue of scale, where while most clerics and white mages and what have you tend to have vastly powerful gifts of healing, they tend to be single-target oriented, which, while helpful, doesn't tend to be extremely useful for an army of wounded (not to mention that most murderhobos consider their droves of allied NPCs completely expendable most of the time).