Most people don't like to come to a site that says their console is losing in sales. Most 360 and PS3 fans prefer not to be reminded that Wii is outselling their favorite consoles. They prefer to go to system war boards and debate on who is going to get 2nd place (winner amongst the REAL next gen according to them 
). They typically ignore the Wii altogether and a lot of the realistic sales data along with it. This is a sales site, and currently the leader in sales trends is Nintendo, thus you see more Nintendo owners interested in sales research because it makes them feel better about their choice and also the excitement surrounding this huge shift in the industry.
If Sony were blowing everyone away, then this site would be swarmed by Sony fans, and if 360 was destined to beat everyone by millions, then these boards would be filled with 360 fans. The fact of the matter is, they aren't so it's not.
EDIT: Oh and the reason why this site's news may seem prominently Nintendo or has a seemingly Nintendo centric twist is because the Wii is selling faster than any console ever has. It is creating an outcome between the debate of graphic progression and new inputs that is against what the industry initially believed. Nintendo also has been declining while Sony has been king, until Wii which flipped the charts upside down. All of this commotion and excitement as listed above is a huge deal on a sales tracking site for market watchers. It is a VERY VERY big deal and seeing just how far the Wii is going to go and how many records it will break and set is part of the fun and intrigue of what makes a site like this so great.
What games we will be playing next generation and what type of consoles, controls, graphics, and styles we are going to be enjoying next generation all starts right here with these sales numbers. These are the best oracle that you could have into the future of the game industry.
