Why is Learning Games Development Hard?

As we continue development on our Pirate science web-based games, we continue to challenge ourselves in creating engaging gameplay with accurate content. Why is it so hard to create games that are fun and educational? Here are my thoughts:

1. Game design is hard. Educational game developers face the same challenges other games developers do: we must offer challenge, character development, engaging story, flow. There are lots of different kinds of games, and lots of game players.
   
2. We try to reach all gamers. Puzzle game developers can be content to develop a game that just appeals to puzzle gamers. Educational game developers try ot reach all potential learnes with a game that cuts across interests.
   
3. Education through game often includes a variety of instructional approaches. If we are content to simply lecture our game players, game design would be easier... yet in game design we try to teach using exploration, inquiry, observation, trial and error. We also try to reach different types of learners: visual, aural, kinesthetic. There is a reason lectures are so common in university campuses across America... they are easy to prepare and execute. When we try to expand on that in games, we are faced with several challenges of varying our instruction.
   

What have I missed? What else makes game development harder when it must educate?