Broader genre representation. Fantasy, supernatural horror and sci-fi are well represented, and slice of life and surreal are not far behind, but there’s not enough mysteries or romances, and definitely not enough westerns. I don’t care for biblical fiction, but a little of that wouldn’t hurt either, and I will never, ever get tired of good historical fiction. Likewise, there aren’t enough “slice of life” settings that aren’t the suburban middle class variety. Other people have lives, too. Show me some of them. There are wonderful opportunities in IF to introduce players to alien lifestyles. Television is at last getting the hang of this, IF should too.
Pushing the boundaries of the medium, oh yes, there’s never enough of that. Self-reference gets old if overused, but peculiar interface tricks and truly subverting expectations makes me go “wow.” Likewise, if you’re going to have a game featuring magic, high tech or super powers, implement it really well and let me do lots of cool stuff with it.
Clever use of language, yes please. It’s a text-based medium, make some pretty wordstuff.
What direction is it going? Well, so far I see a boodle of choice-click games (which I wouldn’t consider truly interactive fiction, more like semi-static fiction, as the “interactive” factor is limited to clicking prewritten choices), written with greatly varying degrees of skill. I’m waiting with trepidation for the day when the fanfic community discovers Twine, frob help us all.
Gonna have to respectfully disagree with Peter Piers about linearity. I want more choices and more multiple endings. A game with only one ending has a lot less replay value. And yes, I persist in viewing IF as being, in a significant degree, about games. If there’s only one ending, then to me it’s not that different from reading a book, except a game requires more input (and in the case of a choice-based game, not very much more input, unless the author has been kind enough to implement puzzles). If I wanted a linear narrative, I’d read a book. Which I do, with great frequency and gusto, but my motives for playing IF are not the same as my motives for reading. There’s overlap – I like games that are good to read – but I also desire games that make me think.