I think when one says things like "The Worst Movie Ever Made" you have to take a lot of things under consideration. I mean Battlefield Earth is a piece of shit for sure but, yeah, it's not worse than many of the movies on MST3K, in particular "Manos: The Hands of Fate" or movies like "The Room" but there's a lot of buts and ifs in the fine print.
Is it really fair to say that Battlefield Earth isn't a terrible movie because there's a self-produced, very limited release piece of shit out there floating on DVD? Or that some asshole fertilizer salesman 50 years ago made a piece of shit on a crank-camera that had a one-night showing that caused most of the cast to sneak out the back door in shame?
I think not. Battlefield Earth gets so much shit because it was a wide, international, big-budget release with big-name stars in its cast. THAT is why it's so shat on by people. It's a big piece of shit because it has no excuse to be one and it's practically unwatchable even though you've got a good, charismatic, actor like John Travolta in it.
Is it worse than "The Creeping Terror"? No. But it's harldy fair to compare to different movies, separated by several decades and produced in very different ways with very different budgets. "The Creeping Terror" is a piece of shit because they lost the audio for the movie (introducing us to narrator), the monster is a Chinese parade dragon and is bland as hell. But it's also a product of its time as movies like that were pretty much a dime a dozen and very much the "B" or even "C" movie.
Battlefield Earth has no excuse to suck so much it was given plenty of opportunity. Sheer incompetence on many levels made it implode.