Good try at guessing my reasoning, but you fail.. In a STREET car, like I said in the above post that you more than likely overlooked, more people (on here) are focused around the way a car pulls in the lower-mid rpm's..
How many 3rd gen proteges are strictly built for drag racing? How many are in the single digits or, better yet, in the 10s?
Im guessing you dont understand the USE of nitrous? Yes, its for a bump in power, but mainly for power in the LOWER rpm's.. I mean, having dealt with nitrous before, surely you already know this..
Nitrous has many uses... on a strictly nitrous powered car (that is, no turbo...otherwise NA) the nitrous is used as a power adder. The aim is to get it on as soon as you have traction and hold the thing down until the end of the track. Twilightprotege's nitrous setup kicks in at 4000 to 4500rpm, depending on track conditions (its computer controlled to come on at exactly the programmed RPM everytime, which helps with consistency - launch RPM is 4000, so any earlier than that is a total waste - but sometimes we need to dial it up to 4500 because the track simply isn't there), both numbers are over half of his available engine speed. Given that its the ONLY power adder on the car, turning it off once you've achieved a certain engine speed would be counterproductive - That is to say, if he turned it off at say, 6000rpm, he would all of a sudden lose (all things being equal) 50 odd horsepower at every point of the curve past 6000rpm, which is considerable, given that he's got a full 1500 RPM left to go before its time to shift gears.
On a turbo setup, it is either used to assist in spooling an overly large turbo, or to provide a top end kick, or both. I've seen big turbo'd drag cars use it as both a window switch to get the turbo on boost, as well as use it right through the track - totally depends on how everything is set up and what you are trying to achieve.
So no, its not just used for gaining "low end torque" as you imply. Its used as an exclusive power adder, a suplimentary power adder, or to get the turbo up on boost (which has zero to do with torque, and everything to do with increased oxygen and fuel and thus greater exhaust volume and velocity. The increased torque/power afforded in this example is simply a byproduct.)
As for torque vs HP, Perhaps the best way i've heard it put is in this post here:
http://www.mazdas247.com/forum/showpost.php?p=4084273&postcount=108
He steps through the maths, and makes an important point about GEARING (in that engine torque is not important - GEARED torque - that is torque at the wheels is what is critical)
Basically you cannot have one without the other - and to say that torque is some how greater, or more important than horsepower is totally wrong. You increase torque at a given engine speed, you ALSO INCREASE HORSEPOWER at that same engine speed, and visa versa. And its the HORSEPOWER that is responsible for making you move - the conversion of chemical energy into mechanical work which drives your wheels and pushes you along.