A lot of it goes back to M:TG, which uses the same concept of "keywords". Back in Ye Olden Tymes, when most M:TG players were coming from RPGs, you would see debate -- real, vicious, debates -- about things like "Can you Terror a wall?" (Terror was a card which instantly destroyed any non-Black creature.) You would have people deciding very arbitarily that you could terror a Living Wall, but not a Wall of Stone, because "It just didn't make sense!"
Well, no, it didn't, if you took the card literally. But the card really was "Remove any non-black creature from play" (and walls were 'creatures' with the 'wall' subtype). It could have been called "Black Card #51" for all intents and purposes.
4e applies this sort of system to RPGs. It's not the first game to do so, but it's the most prominent to adopt the "high wall of separation" between the mechanics and the imagined action. Because the rules do not make this very explicit, and because some of the rules veer towards an older style of game play, it can be very frustrating/confusing. The use of flavor text which "describes" what you do, and the way in which terms are used which SEEM to have a common English meaning, but really don't (Prone, for example -- it applies, as noted, to creatures which cannot logically be 'knocked prone'), makes it less than intuitive that the game needs to be interpreted VERY broadly in play.
The 1e DMG had some long essays on what hit points meant, why you got a saving throw no matter what, etc. It made dealing with the disconnects between game rules and game reality much easier -- no, you COULDN'T get stabbed in the heart ten timess and live, high hit points meant you were stabbed in the leg, not the heart. Etc. Hopefully in PHB/DMG/Etc II, this will be amplified and explained. (Another example -- daily/enounter powers should be seen as "the player dictates an opportunity has arisen to use this ability", not "You 'forget' how to kick someone in the balls until tomorrow." However, a lot of the flavor text for powers which let you regain other powers implies your character, in the game, is somehow reinvigorated. (The 'tiredness' or 'strained' model for limited Martial power is, IMO, pretty weak... "So I'm too tired to use a Level 1 Encounter power anymore, but I can easily use my Level 5 Daily power, presumably a more exhausting power?" To quote DM Of The Rings, "
That's a very specific level of tired."))