Everything in the Prequels is like a bare-bones, skeleton of a story. All the details - all the “connective tissue” - was all filled in later by people who are not George Lucas.
What was Palpatine’s plan in the Phantom Menace? Who knows! He was doing some shady shit with some Trade company to get elected President, that’s all that mattered. Why did the Separatists want to leave the Republic? Who cares! Taxes maybe! Or something! Maybe they were sick of Palpatine’s tacky office furnishings. What about Anakin’s great friendship with Obi-Wan? You know, basically the entire dramatic basis for making these movies? Who cares! It happens mostly off screen. We’ll fill it later with some EU “multi-media” projects or whatever. What really matters is General Grievous has enough screen-time to justify all those ILM man-hours and electricity cost of 3D rendering, and to meet projected sales figures for Grievous toys.