Something Reynard said got me to thinking. When I first started playing D&D, random chance was king. What ability scores did you roll? Did you get a 17 instead of a 16? These things could make a world of difference when determining what you could play, and how effective you would be.
If your DM rolled treasure randomly, a humble treasure chest could pay out in potions of healing or a longsword +3; the original "loot boxes", if you will.
Even some magic items and spells were slot machines; what did I get from my Bag of Beans? What card did I draw from the Deck of Many Things? Did my Prismatic Spray nuke the dungeon boss, or was it a colorful dud? Even the basic game mechanics, did I hit? How much damage did I do? Did I make my save?
Often, it proved that it was better to be lucky than good.
Over time though, D&D campaigns evolved to have ongoing plotlines and became much more than the Rogue-like and Diablo-esque games that it inspired. Some groups began to shun randomness, because it could turn an enjoyable story into a total disaster. Not only did some players reject pure randomness, but even some games did (I'll shill Amber Diceless Roleplaying here as an example).
I often see people who desire more randomness and less at loggerheads about what they feel is "fun". The arguments about monster critical hits a few months ago touched up on this, with a majority of voices seeming to feel that the game would suffer immensely if there wasn't a constant (if low level) threat of being instantly knocked down by a powerful monster's lucky hit.