What's the big deal about freedom in RPG's?

Reviewer after reviewer will tote a game's "freedom" as a selling point. I fail to see how this, by default, increases a game's fun factor. In fact, the term "linear" far from being a neutral descriptive label for a game, has instead become a criticism. The best RPG's have a plot, because that's what really draws you into the game world, and makes you want to emotionally invest in the characters. Linearity cannot be avoided. So when gamers clamor for more in-game freedom, what do they actually want?

I think they want to feel that they have a choice, that their decisions make a difference in the game world. This can be done in many ways, without sacrificing linearity: Character creation, allowing the player to choose the sequence of events (an excellent example is in Star Wars: Knights of the Old Republic. The plot still required certain events to occur, but since the order didn't matter, BioWare gave the gamers the illusion of freedom by allowing the player to pick the order of the star systems to visit), and optional material, such as side-quests and mini-games.

I have the most frustration with freedom via optional material. Sometimes, programmers go so overboard with optional material, that they make it the main point of the game. A case in point is the highly acclaimed game Morrowind. One of its main draws is that it is an "open-ended" game; you're placed into a world, and just let loose to do whatever you want. I find this type of game very boring. Without a plot to give context to my actions, there is no "why" to anything that I do, and running around killing things, or completing quests becomes more of a chore, rather than a fun activity.

In other games, like many of the recent Legend of Zelda games (Ocarina of Time onwards), I become frustrated because it's not always clear where to go next to advance the plot. That is poor game design, and more in-game freedom only makes it more frustrating because now I can wander around this huge world for hours and still not figure out the next step. An example in Ocarina of Time is that some of the puzzles require Fire Arrows to light distant torches. Where do you find these special arrows? You have to happen to pass by a part of a very large lake at the SW end of the continent and happen to see and read a small placard located on the ground that says to shoot an arrow at the sun at dawn from this spot. What in the...!? No one every tells you about this; you just have to happen upon it randomly. I was very annoyed (I had to read a FAQ to figure this out).

In my book, if a game requires a FAQ in order to complete it, it's not well-made, and seriously detracts from the fun factor. I have no qualms with being led around by the nose; after all, isn't that exactly how movies and books are? But in-game freedom, just for freedom's sake, is a poor substitute for quality content. Unfortunately, with all the focus on 3-D environments and freedom of movement, I don't see things changing anytime soon.