True, but Apple generally do care about either size or quietness. Starting with the G5 cooling system they started to exchange a lot of the former for the latter in their large desktops. I expect that is the case here (i've not actually seen a picture of this thing) - However this doesn't mean they designed the cooling system extra large margins, that's just not their attitude, unlike PC vendors they control all the components they can be more exact (Saying this as quite the opposite of an Apple fan boy).
Point is, the cooling system overcapacity is due to expected (but generally not fulfilled) TDP, rather than adding arbitrary large margins.
Yes, although it's worth noting that they seem to have rowed back on this a little bit in their recent designs. The new MacBook Pros are cooler due to the processor being cooler, but they also have feet to allow better airflow under the machine at the clean flat bottom of the previous models (IMO they still look great, but I can't see Apple of a few years ago making that decision).
Their new CPU architecture certainly is more power efficient compared to x86s they replaced in many ways which means they aren't up against such a wall to compete on performance, perhaps a combination of circumstances have caused them to produce more thermally comfortable machines in recent years. I'm not sure how long this will last though... in that sense I'm sure they do have relaxed TDP margins, so i'm basically arguing about the subtlety of this not being an intentionally large margin... now I look like i'm splitting hairs :P but it's clearly a mistake from the analysis of the GPU.
