I don't think so. At the very least, signature restaurants might help children out of their shells with opportunities to try different things (that generally aren't that different).
The one thing I would say is that they should be held to the same standards as adults in such places. If a kid is screaming or running around, that's not fair to others trying to enjoy their evening, and a family that can't control a child should be asked to leave immediately.
That said, I didn't have any problems with children at signature restaurants when I was there in November. In fact, at Flying Fish, a child from an adjacent table really made our dinner better by sidling over to talk to us. His parents apologized for bothering us, but he was sweet and we loved the fact that he engaged us.