Pyke and Dave are supporting themselves by selling games; the Crystal Shards team are not, and neither am I. The entire dynamic changes. In one instance, you're a slave to the market, in the other, you're not. If the market says, "We will only let you feed yourself and your family if you produce games that include no puzzle-friction," you'd be silly to answer, "Well, I'd rather starve than let you breeze through my game, so no." But it's not just economic. Very few people feel a spiritual need to design or implement puzzles; most adventure game developers start from a visual (Chris?) or narrative (Dave?) imperative. Adventure games are a vector to share their art, and whether the vector includes puzzles or not is ultimately of little importance. "Give up sharing your story so that you can include puzzles!" is not going to be persuasive to someone like Dave who has stories, not puzzles, to share.
Even though I'm not much of a puzzle designer, I do feel an imperative to include them, and, as I said, I don't care about the money so much, so it's easy for me to walk away from sales/exposure. It is a little unfortunate, though, because the more adventure developers gleefully denounce puzzles as stupid, archaic, obstructive, etc., the more primed customers are to walk away from games that include them. "If there is friction in a game, it's because the developer doesn't know what he's doing and hates you!" is a way for developers to endear themselves to a mass market, but at the cost of reinforcing the biases that market already has against the core element of the genre. (By the way, I'm not suggesting that Chris or Dave says things like that, but many do.)
Lots of adventure games include unique mechanics -- "parties" of protagonists, action sequences, branching narratives, etc. Of course, Heroine's Quest is much more mechanically complex than Unavowed, so I'm not sure the point applies here. But, for instance, Beautiful Desolation has a bazillion features that Primordia doesn't.
