Sticking rune combinations into then to make them. The suspense of seeing how it rolls after you stick the runes into place. The fact that runewords harbored some of the most powerful and original / game play changing items. (Enigma for teleport, etc..). The fact that you get to choose your base, so superior or crude base items actually made a difference. Versatility of common runewords early on during the leveling process. Different runewords featured for different seasons, incentive to play season, and differentiating 1 season from another. The adding of interesting future runewords to help fill itmlemization gaps. Giving the player a feeling that they have collected all of the required items, and manually forging your runeword rather than just gambling or forging at the blacksmith. I can go on and on if you want me to.