<p>I really think not having Maul be Grievous was a serious missed opportunity.  By taking these two mostly uninteresting throw away bad guy and combining  them they could have actually given him an interesting arc between the movies that would have provided a nice foreshadowing for what was to become of Anakin.</p>
<p>Sure, Clone Wars has done a decent job (I think) of spicing up Maul and Grievous, but these are suppose to be 2 of the 4 main villains in the films (really 3 since one of the villains want meant to be a "Phantom Menace") and that kind of character development shouldn't have been farmed out to the series, especially if you are going to have a different villain in each movie.</p>