On a somewhat serious note, one thing that I think we see that's interesting in the KK movies--especially one and three--is the difference between real karate and McDojo karate.
I don't think it's a kata problem, because I think kata can have its uses. It's more of an issue of the approach to the style.
Even though the script calls for Daniel to win, we mostly see his get his ass beat throughout the movies. His crane kick was one of the very few significant strikes he lands in KK1 and, in all honestly, could probably be called lucky. And in KKIII, Mike Barnes gives up several points just so he can beat Daniel's ass, and this is the ONLY reason that Daniel ends up winning.
Cobra Kai karate was true fighting karate. If that dojo existed in real-life, and you signed up there, you would stand a pretty good chance of developing some actual skills that would help you defend yourself in a street fight (or in a ring with some modification). What Daniel was learning, by contrast, was the kind of karate that ultimately gave karate and other traditional styles a bad name. It's relative ineffectiveness is proven by the fact that he spends much of the trilogy as a punching bag.
We've seen something similar in MMA. A lot of the karate stylists in the early days of the UFC got their asses beat because they didn't really understand their own fighting styles. And then finally guys like Machida, Wonderboy, Makdessi and Gunnar Nelson came along to show that, hey, if you have the right approach to training then these traditional styles can be used to actually fight people and win.
Bottom Line: Cobra Kai Karate > Miyagi Karate.