Supposedly this was meant to be a serious exploration of the contradictions and friction in the counterculture at the time (a kind of continuation of what Nicholson and Hopper tried with The Trip the year before, from what I've read it would have been a logical progression from that through Psych Out to Easy Rider, all three of which were basically made by the same people) but then Dick Clark stepped in as producer and decided it wasn't marketable enough.
It's still great though, probably my favorite of the genre although The Trip, Wild In the Streets and Head are close contenders, too. Like It Is is also great but kind o in its own category, and Skidoo is of course the biggest debacle but it's also kind of boring when Jackie Gleason isn't on acid. I still haven't seen The Big Cube.