There's another Matthew Wood interview
on Starwars.com in which he offers his opinion on Grievous's motivations:
"I see Grievous' hatred of the Jedi stemming from intense jealousy; the Jedi have a skill that has been unattainable by Grievous," says Wood. "Even though the technical skill of the lightsaber has been taught to him by Count Dooku, Grievous still lacks the Force-sensitivity to grasp the true nature of the Jedi. So many things seem just out of reach to Grievous, intensifying his jealousy and frustration."