Because Pineapple Express is a better movie when you're stoned! Seth Rogen's character says it himself; weed makes everything better including movies. Ss that to say that this movie needs you to be high to enjoy it? No, but if you don't smoke weed or aren't high while watching it then it probably won't be as enjoyable. It's a movie that plays to a specific audience and because of that some people will walk out disappointed. Not because it's a bad movie, but because you kind of feel left out of some of the jokes. Do I smoke? No. Did I enjoy the movie? Yes. Do I think it's one of best out of the Apatow machine? NO.
This movie went from a intelligently written comedy to ridiculous over the top comedy by end. In the meanwhile important moments that would normally draw the audience in are gleemed over. I have to blame the director David Gordon Green for this more then anyone else. As an independent filmmaker who has only done dramas it seems that he doesn't grasp comedy. He allows a funny script to play itself out while he sits on the sideline and watches. He doesn't fail in this movie but he doesn't capitalize on the strongest part of any Apatow comedy: it's heart. Knocked Up and Superbad were movies that had heart. They had meaningful moments between the two lead characters that pulled the audience in and that was completely missing in this movie. The only time I felt anything for the characters was when Rogen's character was yelling at Franco's character for being high all the time. Those same emotions should come back even stronger later on when the two characters get back together realizing how much they need each other and they never do.
A few things in this movie do work and number one is James Franco. He's the reason the movie is so funny because he is actually acting. He does so well that Seth Rogen's character comes off funnier then he actually is even though Rogen is doing things the same as he has in his previous movie. It was obvious to me who is better comedically in this movie as soon as Franco showed up. The dialogue was sharp for a good portion of the movie which was awesome for a movie that involved dimwitted stoners. Unfortunately at some point it took a back seat to physical comedy, which can absolutely be funny, but you can't regress to it and never work your way back to what made the movie work in the first place. Craig Robinson also did some great scene stealing work. He continues to get small roles in big movies and continues to stand out as one of the funnier characters.
All in all I would have to say this isn't the best of the Apatow comedies but let's face it his worst is better then 95% of the other comedies out there. I do wonder though if this movie was in Apatow's hands or a director more experienced with comedy if it would be a better comedy. Get out to the theaters and give it a go and don't forget the weed.