The story might be open, but the gameplay isn't. My point is that compared to these other titles I listed, DA:O is a throw back to the classic RPG gameplay of 10+ years ago. I didn't find that type of gameplay engaging then, and I still don't; it's simply a personal preference.The story isn't any more linear than Fallout. In fallout you had to do the story quests in a specific order. In fact, in DAO it splits into several branches you can approach in whatever order you prefer. Some are definitely easier than others but you're not restricted after you do the 'Joining.'
Also, you can do the whole thing in WASD and not use click to move. The point is that you have options, the game isn't rigid.