Well, this is also my first post , so hello everyone.
As for this topic. I have known many gamers over the years, and during my university life and so far short internship in the gaming industry, almost all if not all people I talked to seemed to be able to reminisce about adventure games happily. This is often because of either a challenge involved that they are proud of completing, or of the story that they played through. There will always be a market, who knows how big, for games that have such in them. Myst for challenges as a example. I guess the point I am trying to get at is what defines a adventurer game? Do you have to go on a adventure, is that is, because almost all games involve that. Is it solving puzzles, or a strong story? Games over the years after the decline of adventurer games (I will never say they have died till all such forums like this are gone) have had such. So before we go about changing things, trying to fix everything, and such, figure out what we have to have in a game to classify as a adventure game.
As for some of what people have suggested above. 2D vs. 3D. I see no problem with either. In 2D you get a different feel in the game, viewing it from afar almost in some cases. As some have said, like reading /viewing a book. 3D, you get some levels of interaction not available in 2D. You can also give a greater sense of immersion if done right. I think a big question of this choice should go to the type of story being told. If it your (a random person) story, a 3D view could do a lot of good to all aspects of the game. If it is a story of some person like in the sierra games, the 2D feel seems right to me.
Plot vs. interaction driven. In a adventure game, if the story is driven by the plot, yes, I feel it would end up being like a interactive movie. But to make it entirely interaction driven (use item A on thing /place B ) it ends up being very repetitive and can even get to annoying. As with all things you need a balance.
Choices (being able to solve quests in many ways). The biggest problem with this is why? Sure it allows the player to feel more in control of the actions, but it will likely be only a small percent of the population that try the other solutions. The snake example for example, if you could throw the rock, most people would do that option I bet. Since most people do that, why spend all the time to create these alternate paths through the game that so few people are going to see. Imagine being the person who spend months (or however long) to make the other path (coin -> gypsies -> tambourine -> snake) knowing someone else is just making it so you can grab a rock and throw it at the snake to get pass. I would feel the work I am doing a little pointless (unless you have to do that bit anyway for some other reason). Giving the player alternate choices is great, and I often think (when thinking about game design) about a 4 type of solution to all puzzles. But even then the reason is only for each of the 4 type of players I expect in the game.
Wow, I kind of went on for a bit. I will let people rip this post apart now.
btw: when all my friend talk about Grim Fandango, the first thing that comes to our minds is always the gold flakes bit. We all love that puzzle. And QFG2, WIT is awesome. Tough but awesome.