It could have been neat if ADOM had twice as much content and half as big a game world, portioning out and randomizing the special places from game to game. The bug-infested temple might show up only once every five games, and always with a different breed of vermin -- it would never grow old
On a more serious note: I think a point to consider is how we define fixed vs random content. It is evident from the discussion so far that there is an intuitive definition that's more or less coherent between the lot of us. But if we take a broader view, couldn't we say that a single orc and a healing potion are both examples of fixed content? The orc has its stats, traits, and behavioural patterns. The healing potion has its predictable effect. I guess what I'm getting at is that most content in RLs are hybrids between static and random content. The perfect balance between static/dynamic would result in pleasantly themed encounters which are still never quite predictable.
Rogue mixes and matches arbitrary prefixes ("red", "blue" etc. for potions) with meaningful suffixes ("of healing", "of blindness") to construct the identification subgame. I think a similar scrambling of fixed content could be used to combine several meaningful elements into a whole. To take quests as an example, they follow some fixed patterns: There is a quest giver, usually also a quarry (missing person, stolen item, etc.), an antagonist with minions, a place the hero needs to reach to solve the quest, a landscape s/he needs to pass to reach that destination, etc. Working with a few quest templates, you can add more specific archetypes to the mix: random helpers, junctures where a choice must be made, etc.
Doing something like this well demands that you have a robust framework, which allows different tidbits of fixed content to fetch other random tidbits in a sensible manner (a random artifact should pick powers fitting a certain theme, etc). Also, we don't want a horde of "villagers" with random titles and nothing interesting to say or do, which means we need a lot of really wellwrought content, to come up with NPCs like: A working smith who lives on an island and hates dogs, and whose son has been kidnapped by a kobold chieftan who makes his lair in a temple ruin deep in the forest.
As always,
Minotauros