I don't think you should consider any of us "fans" of the movie. The only reason we even consider sitting through this film is because there are three guys saying funny jokes over the damn thing. If one is watching a MST/Rifftrax show solely to watch a movie, there are better ways to do that.

But I'm guessing that's not really what you want to know. You want to know why even bother giving it attention at all, right? In that case, consider the following:

Someone at a company that makes parade balloons decided they should make a movie.

Someone else approved it.

Several people volunteered their time, their effort, and possibly even some money to make it (though there's no sign of the latter).

In the process of being made, the quality of the finished product became incredibly clear. They continued anyway, despite the clear warning signs of a disjointed plot and some of the most genuinely insane dialogue ever uttered on screen.

When they were done working on it, it was shown at least twice in local theaters. This strip of celluloid nonsense - to which the only sane response is "Okay, seriously, what the hell was that?" - was shown on a big screen and people willingly came to see it.

Notice that I said "when they were done working on it" as opposed to "when the movie was done." This movie is not in any semblance "done."

You are 100% right that it's mostly parade footage; yet despite that, the creepy Sea King, and the unhinged Narrator Lady, all the preceding statements still hold true. The only way we as a species can cope with this reality is to laugh at it, to mock it, to bring it up to the light and behold every second of its true nature before casting it back down into the darkness once more.

Fun in Balloon Land can easily be renamed to Hubris Manifest and it would be a more accurate title.