I don't know. Lifesteal never struck me as that strong of a perk to be honest.
Given the choice I would go for more armor, health and magic resist instead of stealing back life. The reason being that Life Steal only works when you are dealing damage. And there are certainly situations in which you cannot deal damage for some time. Anyone who played WW Barb in D2 knows that if you miss your Leech or you get crowd controlled you are basically dead.
I also feel that with Health Globes, Lifesteal is even less of a necessity.
If Inferno doesn't require you to go for a Lifesteal build, I would always choose more utility over Lifesteal. And if Inferno requires you to take a build which invests heavily in Lifesteal, something is wrong with Barbarian's design.
you probably end up needing both defensive stats and lifesteel; but I agree with you - defense ie armor would be my first priority and then lifesteel ...
I would think Id want at least 1 ability that could steal life to help 'top off' when there are no potions and when you are low (since the barbs passive regen could be a bit slow 2%~ max regen a sec.)
Lots of stuff to choose from - rend, charge, overpower, revenge and hmmm cant remember if anything else.
Keep in mind that Witch Doctors and Monks have a LOT of self-healing abilities (mostly Rune effects), while Wizards and Demon Hunters have craploads of slows and stuns so that they don't have to get hit in the first place.
If you try to make the d3 beta "difficult" by playing entire games naked, you'll find that Potions and Health Orbs become awfully scarce, awfully fast. Once we get to harder difficulty levels, self-heals will be extremely valuable for all classes.