If someone was changing their child's diaper in full view of the lounge, I would surely say something, either to the parent or an employee, when their is a perfectly suitable bathroom that presumably has a changing table. That's what they're for.

One of the things I appreciate about the Centurion Lounge in LAS is the playroom for children. Even though I've never seen it used - nor have I seen children in the lounge - it is nice to provide a place to occupy them and keep the peace in the rest of the lounge.