Justified Expectation of Pleasant Surprises
Very interesting. I guess there are two sides to this. All the best games I've played, going way way back, have contained constant surprise and multiple routes through. A single route and (or) a routemap that says 'this is what you'll learn/unlock here' has never done anything for me. But I think there is also a certain satisfaction in having the big book with the level 9 spells in to contemplate at your leisure, and to imagine what you might do with them if you had them, and how you might achieve them. Even with the level 9 spell book at your command, you know you're never going to have everything, and you're going to have to pick and choose what you hold in your head at any one time, trusting in your best skill to judge the path ahead. And having the book still leaves plenty of room for a few surprises that aren't in the book (the odd unique artefact, for example).