My guess is that a large number of viewers simply just didn't pick up on exactly what was going on.
"I could start watching Episode II without ever needing to see TPM because nothing of importance or of consequence really occurred and that is the real travesty."
And the breathtakingly wrong:
"Although the plot looks long, it's actually paper thin, as the film is really just a chance to show off great special effects and an introduction to some of the characters for the original Star Wars trilogy. That's not to say that this film is bad, it's far from it but it's full of things that the viewer just couldn't care less about e.g the council meeting about how the problem should be solved."
Equally breathtaking:
"As the movie ended, I leaned up in my seat with my mouth wide open. The plot is about problems with a trade federation while the jedi and sith lords jockey for intergalactic position. The trade federation is a completely unnecessary plot and takes away from what should have been the highlights of the movie, namely the introduction of Anakin Skywalker and the struggle between the jedi and sith."
There are, however, a few reviews from people who "got it." If you were one of those who didn't, watch the movie again, with your careful "thinking cap" on.
If you don't clearly understand the title of "Star Wars: The Phantom Menace," then you don't understand the movie.