Tera: It creates an artificial sense of boundaries. It's like saying "dont hunt those mobs because it's less efficient than hunting these mobs over here". It would be cool and truly "next gen" for there to be a fluctuating EXP pool. By that we mean mob "X" may give more EXP than mob "Y" does but after a certain amount of time or after mob "X" is hunted to a certain magical number the EXP pool then fluctuates so that now mob "Y" is giving out more EXP then mob "X" and so forth and so on down the list of all the mobs in that level(buy tera gold) range.
Throw the mob list onto a randomized table and you got yourself a hunt. You would also separate the people who are trying to farm a certain item or a certain material from those interested in only the EXP or you would make the player that is farming and the player EXP'ing clash and fight over the same mob. Both results are desirable in their own way(Tera Gold).
But it would not be so cut and dry anymore and it might add more of a sense of "we are actually hunting the big EXP numbers now" instead of "hey guys lets go grind the same mobs we were grinding yesterday in the same spot. Personally we feel it's time to expect more from these games. More of a sense of adventure(Tera online Gold).