My hospital also told me to not to swaddle, because of SIDS. They also said it was due to overheating. What was kind of funny, was they all told me that they "had" to tell me this, and then they would say under their breathe, 'but I would still swaddle if I were you.'
Basically, the new rule is that swaddling could cause overheating, and lead to SIDS. Also, if not swaddled properly, the blanket could come over the babie's face or get tangled, causing sids.
BUT, if done correctly, swaddling can be wonderful! I chose to do swaddle our daughter because she loved it. (Also, I noticed that all the babies in the hospital nursery were swaddled, even though they told us not too!!) To prevent SIDS, I just made sure to keep in her in light clothing. Usually just a onesie under her light swaddling blanket (she was a summer baby).
And the BIG THING here is to SWADDLE CORRECTLY!! If you just loosely wrap a blanket around a baby, that is not swaddling, and that could be a hazzard. But if the hospital taught you how to correctly swaddle (it should fit tightly, and it should not be able to come up around the baby's head), then the baby will be fine.
I feel convinced that SIDS is one of those freak things, and my heart breaks for anyone who's experienced it. But I think if parents are actively aware of the risks and are making smart choices for their baby, they should let go of the guilt and worry of SIDS.
Good luck!!!