It would be silly to think that Laporta has not learned lessons from the mistakes he did himself during his time as club president, or from watching the trainwreck that has been going on for the last few years under the Rosell era. You can't just say that Laporta in 2015 is going to enter Barcelona with the exact same level of maturity, knowledge and general attitude that he had years ago when he first became president. Yes the football world has learned lessons and evolved since then, but so has in all probability Laporta as well.
He already has experience from being president of Barca, a president that played a part in building the most successful football team ever (of course such a rare event is down to many improbable factors, that doesn't take away from his role in it), he knows the club in and out, and most importantly he is a true fan of the club. This last part is most important for me, because you know he really cares about the sporting success of the team. It's important that the people on top cheer during victories or sulk after defeats just like the fans in the stadium or at home do.
His experience from being president should only count in his favor really, as he now knows better than most what works and what to avoid.