It's great for a number of reasons—we've enjoyed lighting drug fields on fire since San Andreas. But the thing that really puts it over the top is that for a moment, the game's tone completely shifts and Skrillex starts playing.
The tune in question is "Make It Bun Dem" by Skrillex and Damian "Jr. Gong" Marley, and it plays on a loop throughout the entire mission. As Jason takes a flamethrower to Hoyt's drug crop (and the fumes make him get stoned if he gets too close), it's basically impossible not to gleefully grin and jack in another tank of fuel.
I have a feeling this might be the most widely YouTubed mission of the fall, and with good reason. Whatever complaints I may have about the game's story and tonal consistency, I'd actually love to see more stuff like this. You don't have to be Saints Row the Third, but a little goofiness (and a killer soundtrack) can go a long way when used properly. Sometimes you gotta say screw it; we need some Skrillex.