I think they should go even harsher and put the last boss with the biggest XP of them all LOL, this way people have to clear the entire dungeon. Anything and everything to prevent speed runners or those abusive people trying to take advantage the system for the sake of "speed leveling everything".

Honestly, if you are in low level dungeon trying to get XP, you are far better off killing every single creature there. Why skip them? Isn't the point you are there is to level up and not skipping every mobs so you can get less xp?