Sometimes it strikes me how deep the puzzle-centered thinking is infused into the medium. I have played, and been annoyed by, many games that tell a great story and then break the flow by haphazardly cramming in a couple of puzzles, presumably because "IF must have puzzles."
There's one integral, defining aspect to IF and it's the world model. The author creates a virtual world and a story that takes place in it. So far this is only a simulation; to make it a game the author adds game mechanics and they are, more often than not, puzzles. But are puzzles the only option? Is there really nothing else we could do with a virtual world?
What about puzzleless IF, I hear you ask. There are a lot of those, right? Sure, but most of them are just puzzle games without puzzles, or with trivially easy puzzles. Removing puzzles and adding nothing in their place does not improve the situation. Without any game mechanics IF turns into hypertext fiction.
Galatea and its descendants are good examples of non-linear stories with strong non-puzzle game mechanics, in this case conversation. If I may take a look into the crystal ball, I suspect that in the future the puzzle aspects will diminish or at least they have changed considerably. Just like mazes and hunger puzzles have made room for better puzzles, the puzzles we write today will make room for even better design. More importantly puzzles will not be considered the only or even the primary option for IF game mechanics.
The key is to realize that puzzles are just one option for IF game mechanics and they are prevalent (I suspect) mostly because of tradition starting from the very first Adventure. "An adventure game is a crossword at war with a narrative," the famous quote by Graham Nelson from 1995, has been the guideline for IF design. I'm afraid we're stuck with conventions that have grown to define the medium and are now preventing us from seeing more options. It's time to look farther and create something new instead of just improving what we have.