Yeah, having a large health pool on Hell with damage difference makes it a lot easier, but on Inferno even with 44k hp, and tons of reductions, the mobs in act 2 hit me for 7-12k per hit, the bosses/rares/champions do more or 1 shot, assuming I'm not using the 35% rune, even when I use vitality builds, I end up putting that rune on, simply because any rare will do more than 50%.
Also, Wizards have absolutely no kitability in inferno against rares, you cannot outrun even the lowest mobs, let alone jailer/waller/x/x/x, teleport even with the farthest distancee rune doesn't escape their aggro, they'll just keep coming and eventually catch you again, the cd is way too long for combat and even just running away. The slows we have all work decently on hell but all freezes last like .5 sec on inferno, slows do like nothing, you can kite the regular lowest tier mobs on inferno using slows, but no hope of rares unless you find some seriously lucky affixes.
The biggest killer for Wizard in comparison to other classes, is they have absolutely no heal, the only thing close to class regen they have in a skill is that passive for armor, and 310 HPS is like a single level 60 item property, and that's if you're willing to give up a 15-20% damage bonus, more AP, or slows, etc for it.. If you go wit ha health pool build as well, 310 HPS will do nothing towards your 44k hp.
The heal on blades is only 8% and only has a "chance" of activating off the amount criticaled for, the life leech rune for magic weapon is also pretty worthless unless you have some serious DPS and can keep up a constant stream of damage, but even then 1.8% of 50k will only be like 700 hps asumming you can sit there and attack, that's not going to help vs the 5-7-11k-1 shot hits from 1-3-5-10 mobs.