I tend to generally distrust doctors, though my opinion is increasing as I realize the amazing stress they are under with uninformed patients, outrageous insurance premiums, heavy drug marketing, and lawyer sharks constantly circling.
But I detest well child visits. What is the point of taking all the healthy kids and having them sit in the same room, breath the same air, and play with the same toys that all the sicks kids touch? The dark and cynical part says that the point is to stay in business; the kind part says that they can see more patients if the patients come to them, than if they go to the patients.
In the end, I've decided that the Heisenberg Uncertainty principle applies. You can not measure the health of the child without affecting the result.