1- Less muscle breakdown. I know you've heard that glucose is the only element used during HIIT and that's correct. HIIT is anaerobic work, but it is also much shorter than those slow jogs. Think about it, it would take you one hour of long and steady jogging to begin burning anytime of significant calories and once you're finished with it, you're done burning fat for the day. At the same time, HIIT is using glucose for 20 minutes and sky rocketing your metabolism for hours and hours after working out. Which burns more fat? HIIT.
2- Less boring. Motivation is key to successful transformations; you have to want it. Which do you think you're going to look forward to? High intensity cardio. Why? It releases hormones that keep you motivated like epinephrine and norepinephrine. These hormones rush the the energy levels, making you burn about twice the calories. It is adrenaline. Think back to the first time you watched the Fast and The Furious and those guys hitting the nitrous oxide in their cars. That is your epinephrine kicking in.
3- Less time. That's right. Burn MORE fat in LESS time. It always depresses me seeing the guy get up at four o'clock in the morning to do his one hour jog around the city, half asleep, and bored to death. I wonder what he would do if someone would tell him that he can burn the same calories in twenty minutes with a more motivating style of cardio.
4- More power production. Power means work per unit of time. Essentially, this means your ability to explode and be quick at something. Sprinting increasing your ability to have a burst of performance. You get better at what you practice, so if you think slow jogging is going to have better carryover on the football field than fast sprinting and confusingly different paces of speed - you're wrong!