Boost experience earned to encourage leveling. Looking at skills, they are very slow to level up and doing so is not very rewarding for the time put into it. By the time you reach certain levels to unlock aspects of that skill, it becomes irrelevant due to the progress you have already made in the game (this is can be seen drastically with skills such as herbal-ism or fishing, where well over a hundreds hours of grinding needs to be done to reach milestones and small bonuses. These would be okay if the leveling system were faster, and thus more engaging to the player, but at the current moment it just feels like something in the background and not really worth delving into any sort of grinding.
TL;DR Very big grind for small payoff, make grind shorter and more rewarding as a result. Even cutting skills in half leaves hundreds of hours to grind.