The idea is to foster lifetime media-consumption. From the article:

That initiative appeared designed to assuage industry fears that young readers don't share the same appetite for print media that their parents and grandparents have, denting current and future revenues.

"The habit of reading the press is learned very young," Sarkozy said

It's the same reason why banks created special bank accounts with all kinds of perks for teenagers: they know at least X% of them will be life-long customers.

I'd never suspected, but I actually like this Sarkozy idea. Money going to fighting illiteracy and improving education is always a good thing.