Sen. Reid says that promise didn't actually promise what it promised,

and besides "I HAD to do it to keep costs down, so shut up and stop causing problems."
The internet is buzzing today with the news that Harry Reid quietly inserted a loophole in the Senate health care bill that would let insurance companies put limits on medical care for folks struggling with costly illnesses — angering patient advocates, and in apparent violation of a promise made by Obama this fall.

But in an email to me, Reid’s spokesperson defended the move, arguing it was necessary to hold down premiums.
My first thought is they're playing "Maybe we can bribe the insurance companies with this to shut them up." And it won't keep Obama & Co. from trying to destroy private health insurance down the road, so breaking this promise won't mean much to them(as if any of them really do).