Mostly marketing. People who want speed are willing to pay. The other reasons? No camo and no Disapator Pads. Other than that the other bows are the same bows that have longer strokes, thats all. You have to ask yourself, do you really want to cock 225 lbs rather than 150? Do you want to reserve strings often? Do you need more speed? Do you need a camo bow? Do you want more noise on the shot? Is the deer more dead with more speed? Can you estimate 30 yards? etc, etc, etc. Aside from all that it is considered an "entry" bow but it isn't, it's a great bow.
Oh I forgot to mention. I also own a Phoenix, an old Exocet 165 and an Exocet 200