It is highlighting the fact that children can be hidden away for 13 years without being found, all this father did was change the boys surname.
The schools should keep an eye on the missing persons list, it would have had a picture of him, he could have been found sooner.
It also keeps hope alive for Madeleine as she too could be going to school undetected.
The thing that struck me was that some little girls who were mistaken for Madeleine had a similar eye defect. I think one or two looked so like her that they were eliminated by DNA tests.
There is no reason to suppose that the person who stole Madeleine might not have made use of that information.
For example, falsifying results and speaking to the education authorities as a concerned parent whose child was always being mistaken for Madeleine which caused distress. The school in which the child was enrolled would then be in a position of trust and would protect the child ~ and thus the abductor ~ from all enquiries.
I am not saying this did happen ... but it is a way of getting round the eye defect, which apparently might be less noticeable as she ages, with minimum effort. Madeleine could therefore be hidden in full view.