Most people say that weed helps them be more creative, which is the opposite of the South Park quote. Having creative thoughts and dreams but not acting on them can lead to depression. "Being in the moment" is doing what you are thinking, and not letting worry or doubt stop you. Hence the creative energy people often get when high.
Good point - personally, I am skeptical whether weed increases creativity. I never experienced that. I just don't like the weed-bashing from the angle of the you-have-to-be-productive-dogma.
When I was younger (in my early/mid 20s mostly) I enjoyed it and in some ways I think it can stimulate creativity. The way it always felt to me was that it made me think "tangentially".
The stereotype of an absent-minded stoner is one way to look at it, but I often found that it caused my mind to wander and occasionally follow trains of thought that would normally be cut off earlier by "normal" thought processes.
That said, letting your mind wander can spur creativity and cannabis is something that enables this state. At the same time, if all you do is come up with random ideas (some of which might have value to yourself or others), it's only the start of the process. Brainstorming is great but if it never goes past the daydream phase, it may be irrelevant.
Either way, as I got older I stopped reacting positively to cannabis and I find it makes me more anxious than anything these days (yeah, yeah, I tried "that one strain I just had to try"). For whatever reason my brain just doesn't like being in that state anymore. But I'd never tell someone else how to relax or when it's valid to indulge in a bit of daydreaming if it agrees with them.
