Hey kid, we have different stories about it.
What do you think about building storyline mechanics with respect to different difficulty options?
I mean that gameplay would vary not only in difficulty, but in storyline or amount of quests that player receive.
It may look like developer have to build handful unique stories and will demand double of money and HR. My idea is to build one complete main plot and set of side stories/quests, and until certain difficulty modes (suppose those 3 special most difficult goals) player wont get all side quests (developers may even randomize offered set) and may be restricted to go through some predefined shortcuts of main story. Another possibility (along with hiding some secondary quests) will just end main plot and propose to continue (or even restart) on full difficulty to see extension of story.
P.S.: I know that this may require additional funds, however perhaps not as many compared to the interest shown by players. Many games struggle to attend audience more than once. Such feature may add motivation, and different gaming experience. Instead of single pass, players will become interested to go through the game again. And of course, adding more arbitrariness of gameplay will reduce significance of pass-through "manuals" which will inevitably rise over the internet with time.