Alfonso, do you think that they can afford to not play him? It's just the way it is, more given current Barca situation.
Also it's part of the deal with this kind of very skill fellas since EVER, everywhere. It's fair? nope, it's risky? no doubt, sometimes Clubs are in a situation to risk it in a more cautious way? yeap, not current Barca.
Even in recent times, when Messi arrived, him too was constantly injured, there was a risk there and even if the situation was better for Barca in general so that they can comitt to recover him time and again with more time, once Pep arrived, they just hadn't that option and they had to bet on the lad and happily things turned for the best, but the risk was there too, people forget how many injuries Messi faced during his first stages.
And when I say ever, it's because Pele, Maradona, or even lesser players like Aguero also PUT themselves into the first team since a very young age, their clubs can manage that situation with more time or less, depending on their situation.
So it's not just Barca, I witness a cemetary of really talented kids from Boca that got injured being very very young and never where the same after those.