Background work - My point of view
Even though there is lots of background work here, despite what you heard it's a great way to learn the ins and outs of being on set without being put on the spot.
This is especially useful for children just breaking into the industry. If you have a shy child, this helps them loosen up. They get to meet new friends, interact with the principle actors and prove themselves worthy to the set staff. From there they pick up amazing acting skills and techniques.
My daughter began as a background, then became featured, then SAG waivered. SAG waivered is even more exciting because you'll interact personally with the principle as you may have several scenes with them, be featured on television. You'll actually be recognizable without pointing arrows and pausing the television to see your child