The problem with a lot of games that claim to be replayable is that you usually have all the information after one playthrough, the only thing that makes a second playthrough of a game really meaningful is if you don't get all the information about the story just from playing through it the first time.
To me a good game with replayibility allows to approach the same content from a different perspective, but it doesn't prohibit players from experiencinf most of the content in each playtrhough. Fallout: New Vegas is the golden example for me - an order of doing stuff, whom we ally with and whom we destroy can change in each play through, plus each play through wil have different flavour based on the build we run. I prefer linear-ish, but complex and flexible game, over multiple exclusive, but rigid paths.
As long as I can replaying the game and do enough of the things differently, I will be happy. To me reactivity is there to create ilusion of choices, not to force players to do multiple play throughs. I don't think the player should feel like they are missing something major, if they don't do multiple playtheoughs.
