This isn't exactly a request for games, but I'd likely be interested in any games that have this feature.
Are there any games other than Morrowind that have a conversation system like this? I guess you would call it "wiki style". You'd think that by now another game would have used a system like this, maybe even improving it with topic categories and a search function, but I've never seen another game try this. Is there one out there I don't know about?
Shadowrun for SNES has a keyword convo system like Morrowind. Until someone mentions the keyword you don't know to ask about it. Unfortunately, it also clears keywords occasionally for quest reasons because you won't need them anymore, but you can go back and learn them again I think.
The earlier Elder Scrolls games have keyword systems. Daggerfall is pretty buggy depending on the build, but it and Arena are also pretty incredible in terms of the game systems they got into those early games. Arena has destructible walls for example.
Exile: Escape From the Pit (and I guess Avernum, the later revamp might still have it) has a keyword convo system where you type in the keyword, from what I remember. Meaning if you know terms you can ask people early in the game on a replay. From what I remember, the conversation wouldn't highlight terms you could ask about further - you just need to watch out for topics you could ask about. Ignoring common words like "and", "the", etc. Unfortunately, again this is my best recollection, there was no downside to asking about everything. To save time I wish there was some kind of keyword saving system where you could keep say 20 keywords in a saved list and if the NPC would answer anything interesting to them they would be highlighted in your list. Instead you'll find yourself typing the same six words to ask every single NPC because it sometimes coughs up info.