Like any media content there is no right or wrong answer. Some Grimm tales are great and a lot of fun. Some are very strange.
Parents need to make the decision as to what is appropriate and when it is appropriate for kids.
I have no clue how old Andy's kids are or what their personalities are. I'm in no position to know what his daughters should or shouldn't be exposed to. Or how he approaches it, explains things, etc...
For me, I doubt I'd read these to 3-6 yr olds. At 7-10 I could have a lot of fun with these. Religious stories are the same. Most younger kids don't fully understand the concepts of Faith and God anyway until a much older age. Heck, I don't think many adults do!!! Just because the Cain and Abel story, and the story of Sodom and Gomorrrah is in a Children's Bible doesn't mean it's OK for all ages of kids.
In addition, what's OK for one kid at 6 might not be OK for another kid at 6. All kids are different and have different sensitivities to different things.
It's no different then deciding at what age to let kids watch certain movies or play certain video games.
Craig
PS> Andy - I bet you didn't think a Kid's story would so much activity!?