On my lvl55 monk that just finished act1 Hell, I'm starting to find that all the vitality on my gear is making Breath of Heaven (the aoe heal, 15sec CD) not that great, it's only 7k of my 28k HP. So as Raven said, with higher gear levels, you need to start relying more on healing that scales with gear.
A lot of healing comes from pumping the heal mantra to put up the absorb shield that scales as 15% of your max health. Generating spirit for that is how you keep yourself and your party alive.
EDIT: lvl60 for a bit, and have spent some time playing with people that are starting to make progress in act2. The % of max HP heal was nerfed to a max of 1k, which makes this whole approach not viable. Inferno act2 seems untankable, I just avoided elites on the way to kill Maghda, then went back to farming act1. My current setup is Evasion mantra, stacking one resist stat really high (one with everything), life per hit, dual wield fast weapons, heal, cyclone strike w/dodge, or mystic ally. I only have 27k health, but my effective health taking into account my 524 resist all lines up ok with other people that have higher HP but didn't stack resists. I still can't stay in and melee most elites in act2, and neither can they, so it's still just about the uptime on the immune bubble and heal-fear and aoe blind, as far as getting damage into elite packs. In act1 inferno I can comfortably tank molten elites in early act1, and often kill elite packs without dieing even once. I have dex, vitality, and lightning and/or all resist on every piece of armor, some with bonus armor too. Life per hit on neck and weapons, running 600 total. More would help some, as would attack speed. 10k dps is a bit low for inferno, but farming act1 still goes decently quickly solo.
I run this build most of the time, switching up the primary to FoT thunderclap for faster spirit gen and mobility in some situations. Also switching up the runes on the other abilities esp. sweeping winds to the longer duration one for packs where it's harder to refresh while running out of stuff. I change some glyphs for more damage output when soloing, since I normally run with a wizard
It is fully possible to solo with this build, it just takes longer on the easy stuff, but will let you actually win against some of the hardest combinations of affixes. Sometimes you have to graveyard zerg a really nasty pack, like arcane frozen jailer, that will lock you in the path of cutter beams. I rarely use lashing kick, except for damage while solo, or for the knockback situationally while grouped, or on a treasure bandit.
For simple grinding of large groups of weaker monsters, heal on hit is AMAZING when tanking a ton of monsters. Putting the best amethyst you can afford in a socket on a weapon is one way to get more of this stat. Flawless square gems are the highest you will find on the AH with any kind of supply. 65 hp per hit is pretty strong.
I think almost everybody takes Transcendence for heals per spirit spent (only scales with level, not gear, but it's still pretty solid. I run with that, dex->armor, and resolve (25% demo shout on mobs I damage). I assume resolve stacks with the crippling wave, so monsters are left doing 0.75 * 0.8 of their full damage, with slowed attack speed. (Although this depends on me hitting them frequently, which doesn't always happen when running away from nasty elites. Sweeping winds is your main source of damage on multiple targets, as well as keeping up Resolve on anything that gets close). I'll probably drop Resolve from my build, for One With Everything to survive the elemental damage from monsters I'm running away from and not hitting.
For harder survival challenges like molten desecrator frozen elite packs, or similarly nasty affixes, we finally get to the answer to the original question: pump Mantra of Healing with Boon of Protection. 3 seconds of much higher hp/s, the Transcendence heal from spending 50 spirit, and very importantly, 15% of your max HP as an absorb shield that lasts 2 seconds, for you and your party. Finally a heal that scales with gear.
Staying alive is a matter of building spirit any time you can without standing in bad stuff, and pumping your heal mantra every time you are low health. On monsters that you can't just stand and tank and generate a lot of spirit, you can't really spend spirit on offensive abilities at all, just Breath of Heaven, Serenity, and your mantra. Damage output mainly comes from Sweeping winds and your spirit generator. Or much more helpfully, a friend playing a wizard. Your job is to keep them alive while they dodge ranged attacks as best they can. The range your mantra is MUCH farther than the range on Breath of Heaven, so often I'll pump my mantra if my partner is lower HP than I am.