Looking back at the past decade, it really hasn't bothered me that much. Especially in the more recent years with noise cancelling headsets and all. The times I have seen babies/toddlers in premium cabins, the parents (on average) are very conscious of their cabin mates and do everything in their ability to limit the disturbance. All of the horrible experience with irate children have been in coach. Many times, I have seen parents just give up and no longer care as they are seated in coach. I clearly recall a flight from MUC-JFK where the flight attendant had to ask the parents to at least attempt to control their two kids (imagine crawling into your row, tapping your arm, tugging on seats, etc.).

Maybe it's me being numb from too much business travel but this has been my experience.

For the comments that kids have no place in premium cabins, I don't use that hard/fast rule. In my time, I've seen far more adults that had no business flying in a premium cabin (or on a plane no less) than a child.