LeBlanc is fine the way she is.
She's a lot like Kassadin - designed to shut down the enemy AP mid, at the expense of being an assassin and therefore not being a big influence in teamfights save for cleaning up and bursting a couple stragglers here and there. She isn't made to carry like traditional mages (Annie, Veigar, Anivia, Cassiopeia, etc.) and her best shot at doing that is to abuse her earlygame power by bursting the other mid at six and going to roam and push as much as she can to feed her midgame before she drops off at 35 minutes. Asking for a buff is pointless.