I see where you're coming from, I really do.
It's important to note that I'm not arguing in favor of a healing class.
I'm arguing in favor of a single healing skill and a passive. This was made pretty clear in that first monolithic post of mine (I assume you didn't read it. But that's ok. I don't blame you).
My argument: 1.) Healing skills have been in the Diablo franchise since it's inception.
2.) They add depth to a character.
3.) I don't want it to be a direct, one-shot, heal spell in the vein of Holy Bolt (despite loving it) because I know that wouldn't work with Diablo 3's pace.
4.) There isn't a reason a healing spell couldn't have a secondary effect such as an additional buff, AoE, cooldown, +recovery rate % over X seconds, repulsion of monsters, or even damage (though that's getting awfully close to the WD spell).
Arguments against it: A.) Healing must be overpowered so it won't work in Diablo (see #4. The bit about cooldown)
B.) Healing must be underpowered so it won't work in Diablo (see #4. The bit about secondary effects)
C.) Healing means you sit still, not killing and sitting still, not killing is not kosher in Diablo games (see #3+4)
D.) Healing doesn't belong in hack and slash games (see #1 and 2)
E.) Monks kill things (see #5)
I'm missing a few points on both sides but I'm sure you get the gist of it.
Q u o t e: Diablo 3 is about hacking and slashing. Aka fighting. Unless the healing is a secondary effect of the fighting (see: Health globes. Leeching), it is not a part of Hack and Slash.
That holds about as much weight as saying the group buffs have no place in hack and slash games. Hence me citing D3's warcry.
It's an example that there are group buffs in Diablo 3. A healing spell could easily function in the same way as a buff. Over time, unspammable, expensive, but very beneficial to the entire party (and yourself for single player).
The reason why I keep referring to a "healing build" is because of my familiarity with Diablo 2 in that a single character could only focus on a single purpose.
What I really mean by that when discussing Diablo 3 is a single healing spell and a passive bolstering the healing aspect.
And as far as we both know, leveling two skills still leaves room for formidable offensive capability in Diablo 3.
I still haven't seen a reason against it that couldn't be ironed out with balance or creativity. When I do, I have no qualms over conceding.
What happened to the Grug club by the way?
Edit: This single page is probably the largest wall o' text I've seen on a forum in years. And it's about healing. This is why I love talking about Diablo 3.