I disagree with OP. I find that there are plenty of educational games that can be fun and engaging for children. I myself loved Reader Rabbits Interactive Math Journey, along with Math and Knowledge Munchers Deluxe.
I would admit to there not being a lot of educational games targeted to adults. Most educational games I played/have seen are point and click or typing. I would say Typing of the dead is an adult educational game, it being an exercise in learning to type without looking at the keyboard and it being a rail shooter.
Another problem is that the aesthetics that draw children might not draw you or other adults in like, Dora the explorer, The Magic School bus, Schoolhouse rock, Reading Rainbow. Unless they tickle a bit of nostalgia for you I wouldn’t expect adults in mass to watch it.
So in short educational games for children exist, educational fun games for children exist (fun being of one’s opinion), and educational games for adults exist that can be fun. The large problem I’m hearing from you are there aren’t ENOUGH educational games geared to adults or to educational subjects beyond elementary school level, which I would agree with. But to say educational games are fiction and dotn educate i'd have to disagree with you on.