Lets look at it this way Say average level 40 has a max hit of 60 (meleeing) and level 40 pure (str pure) has a max hit of 160. If defense was mitigation, the average level 40 would hit near constant 60's. While the str pure would hit 100's or 80's, he still has the ability to miss if his attack level is low however so they would be about even. Since both parties are going to be hitting fairly often it makes the fight a bit more interesting by having constant damage. However KO's would be pretty rare like this. But that allows Jagex to add in Super weapons, as it stands now theres too many things in near KO range. If Jagex changed defense we could have room for better weapons. Its the change that needs to be done, but it obviously would be very unpopular and change runescape as we know it. But its the only way to get rid of pures (to those against them), allow for combat skills to 120 (defense can handle the extra damage being delt), and have room to throw in new super weapons. I can tell you've never pked before. Pures are severely underpowered. You might have had a case in early 2005 for defence being underpowered, but not anymore.