Went to see the 25th anniversary of The Phantom Menace in the theater last night with my two oldest sons. I actually always liked that movie. Not perfect by any means, but still really enjoyable. The lightsaber fight with Maul is the best lightsaver fight in any Star Wars film or show. Also, every time I watch TPM, I am sad that we didn't get three films of Maul being Palpy's apprentice. Such a shame they "killed" him off. Dooku was a stupid replacement.
That was one of my thought as well, as cool was Christopher Lee, it should have been kinda natural that Darth Maul would be the "second bad guy" of the prequel trilogy, the face of the Sith the Jedi would see while Palpatine was working both sides behind everyone's back; they still could have had an awesome duel in Phantom Menace with Maul suffering a tactical defeat and escaping somehow, and eventually he could have been the one to be killed at the beginning of Revenge of the Sith.
I understand that, for the political side of the story, a more refined character like Dooku was needed, Maul was just a thug and a brute enforcer, but there could have been ways to tell that kind of story and have Maul survive. It would be a natural progression - Anakin defeats Maul, one of the villains of the prequel trilogy, and then takes his place as Palpatine's apprentice and becomes the villain of the prequel trilogy.