Jon Bernthal! That is a good frickin choice. I love Punisher. I think most people do because we want someone like him to exist to right the real wrongs out there. If you consider the popularity of shows like Dexter, it shouldn't be surprising. A killer of killers. The concept is appealing because it touches our primal instincts. That someone could prey on the predators in society. That there is something monsters of men have to fear at night.
There's this line most vigilantes don't cross because they don't want to become what they fight against. Frank Castle doesn't have that line. At all. He doesn't see mafia henchmen, child murderers, serial rapists or other hired killers as humans, but rabid wolves that prey on the innocent. He doesn't believe in caging a rabid wolf in the hope it'll get better, he puts the animal down so no one else can be hurt by it. Because of this, he rarely has repeat villains.
I think introducing him in a series format is genius because, while I love the movies, they would never be big. They can't. He is a solid R rated character and parents aren't really thrilled about bringing their kids to see a comic book movie that's rated R. People not into comics won't be likely to see it cause they won't know who he is. But by introducing him in a successful show that is set in a darker setting, with a great actor that can do intense roles, it shouldn't be hard to spin a Punisher show off of it.
Punisher plays a role in Civil War in the comics, albeit a small one. Having the option to use him is just one more tool at Marvel's disposal. There's this great scene between Punisher and Captain America where Cap just beats him senseless and Castle refuses to raise a hand to defend himself. Cap wants him to fight back, he's a killer and he goes against Cap's morales in nearly every way. Frank on the other hand sees Rogers as a good man and, while Cap wants to believe Castle has no morales and is just a plain killer, he simple states he won't raise a hand against Cap. He doesn't attempt to rationalize or explain, he just takes the beating.
Of all the characters in the hero catalog, the Punisher is the closest one to reality. More than one person with high levels of training have talked about how they have given serious consideration to going that route. To actually going out and taking their training to hunt down and stop gangs and other hardened criminals. I will not be surprised if someone finally takes action.