Ah, but why would you buy a Honda just to take out it's old parts and put in higher-performance parts? Because you're a bike enthusiast who knows that they're doing, and want a high-performance bike that beats the average stuff out there.
People don't always build rigs for performance purposes because not all PC builders are PC enthusiasts. There are many who want to spend as little time/effort/money as possible on building a machine that will simply do the job - which usually means sticking with the stock cooler