To a certain extent, things already seem to be going in that direction-- the Gift of the Naaru is pretty much exactly what she's talking about, except that it's only for Draenei. And Blood Elves, with Mana Tap and Arcane Torrent, have what you might call a "flash mana heal." Additionally, lots of high end gear is showing up with a chance to heal on it-- there's even an enchant now that periodically heals the whole party. Mobs are hitting harder than ever, but there's also more ways to recover from it.
But MW wants a "heal yourself, nub" heal-- for rogues or casters who don't manage aggro, or warriors who don't wait for mana. That idea I'm not thrilled about-- one way to "train" a caster not to pull aggro is to simply let them die. If we gave casters all kinds of outs, there's lowered incentive for them to do their job right in the first place. Of course, MW does say that each class would be required to spec a certain way for the heal, so it wouldn't exactly be free-- players who could play their class right could spec a different way and take the bonuses that came along with it, and players who wanted things to be a little easier could spec for the flash heal.
Then again, by the end of MW's piece, you can tell she's just ranting about being told to heal. That I can identify with-- if I'm main healing an instance, you don't have to tell me to heal you. If I'm supposed to heal you, and I can heal you, I'm healing you. Whether every class has a flash heal or not, if you're not the warrior and we're all doing things right, you probably shouldn't be getting hit in the first place.