granted most people would look into larger boxes for their 1st attempt in building a new box. but that's mostly because they don't know any better. smaller boxes actually has superior airflow patterns since the cooling air doesn't have to travel as far to reach the heated components and less airflow is required to achieve positive pressure. a well designed case such as TJ08-E has superior cooling then most full atx cases since the cooling intake air is less then 6 inchs away from the components that needs to be cooled. it's not till you get into an overkill situation that you can out perform a TJ08-E from a thermal / acoustical point of view.
IMO, the progression towards smaller computers is the way of the future. current standard of 1080p can easily be handled by a single vid card and power consumption will drop as we start going into 22nm process or smaller, there wont be much reason to go with a full ATX cases except for epeen purposes. most people have room for a mATX box like dell, but very few people have enough room for a cosmos2. especially considering that more and more people are starting to use their 50inch LED TV as their monitor when gaming it's just not realistic to expect a large computer next to the entertainment center when a mATX can do the job.