Ah, well. We can do better than that, surely.
So who would we use to produce it that we could be sure to push the envelope as far as PG13 would allow? Someone good at getting crap past the radar.
You know what? You'd basically need someone who doesn't answer to the system, someone with enough clout to do whatever they want. As of now, there are basically only four guys in the industry who hold that type of power; Spielberg, Lucas, Cameron, and Jackson.
Spielberg tends to not take an interest in violent/realistic action scenes unless it's based in a real-world context, like Ryan. A lot of his stuff implies things, but almost always in that accessible fun summer movie context. And he doesn't seem to have his heart in the "alien invasion" sci-fi scene anymore, saying he prefers to try something different from his earlier work. The alien/interdimensional stuff in Indiana Jones was Lucas's idea, and we know how that turned out.
I won't even go into detail on Lucas. Dude lost his mind a decade ago.
Jackson...meh. He's a great director, but again, he's tied down with directing Tin Tin and producing The Hobbit and a bunch of other sci-fi movies for a long time to come. Plus, he does "epic" really well, something Animorphs doesn't really need a lot of. Giant battles are a no, skirmishes and hit & runs are a yes. Although, one thing I will say for Jackson, he knows how to make action scenes really hit home, the guy's pretty brutal.
Which leaves us with Cameron. He wouldn't be interested, since he's tied down for the next few years with his Avatar and Battle Angel Alita movies, but since this is all hypothetical anyway (I don't
want there to be an Animorphs movie, at least not for a good decade or two until it's perhaps visually feasible), he'd be about the only one who'd have the power and perfectionist mentality to make it work. Although, he just about always only works from scripts he's written, adaptations are rarely his thing aside from Battle Angel. Spielberg would perhaps do just as good a job, if he were inclined to not take any creative liberty with it, mix it up to his own ends. A lot of Spielberg's alien stuff is quite kid-friendly and hopeful, I'm not so sure he's deal very well with a covert alien invasion. He's done War Of The Worlds, but his War Of The Worlds sucked majorly.
Spielberg/Jackson/Cameron. Of the three I believe only Jackson would potentially be interested, and he's the one of the three I
wouldn't want to direct this, out of personal taste. I'm sure he'd make it cutting-edge and he'd be able to handle the violence, perhaps better than Spielberg and equal to Cameron. But his actual directing style just doesn't really fit. Jackson always goes big in his studio movies, he hasn't done small and low-key since about 1992.
So, Cameron. But Cameron won't consider doing it, at least for another 15 years or so.