While Kotaku are a bunch of huge huge 360 fanboys, I still think attach ratio is important if you are trying to show whether 3rd party games sell well on a platform.  Of course, attach rate isn't the only metric of success (evidenced by your PS2/GC example.)

Why does attach ratio matter? 3rd-parties only really care about raw sales. Xbox and GameCube had much higher attach ratios. 360 attach ratio in Japan is killing PS3 and Wii by a ton. The higher-selling systems almost always have lower attach ratios, since you have a more diverse and casual userbase, rather than a system just selling to the hardcore users.

 Attach rate is meaningless when compared to raw sales. If there were 5 Console Xs in existence, and every game had a 100% attach rate would it be worth it to develop for the platform? No, of course not. Looking at the attach rate of specific titles in a similar genre can help guage a few different things. The numbers would need to be analyzed into oblivion of course, but it could mean something. When you blend every genre without factoring in budget, advertising, and a host of other figures as well you get a meaningless number that can be used by fanboys to insult a console and nothing more.

I remember when people stopped making games for PS2 as soon as they realised the attach ratio was so low.

Given that your entire existence on this forum is meant to troll the Xbox, I figured you would say something like this. But you would be wrong.

http://vgchartz.com/hwlaunch.php?cons1=Wii&reg1=America&cons2=PS3&reg2=America&cons3=X360&reg3=America&weeks=100

Comparing the PS3/360 hardware sales in America shows that the PS3 is not actually that far behind the 360 when launches are aligned. The PS3 third party software is actually quite far behind the Xbox360, it's clear that the PS3 not only sells less third party games, but at a lower attach ratio than the Xbox360 did.

Wow a lot of Kotaku posters are very childish... Glad I am boycotting childish posters.

PS3 third party sales are terrible and third parties have probably spent tons more cash on PS3 development.

However using basic extrapolation techniques we get this;

We didn't say Third-party games do not sell on the Wii.

We said GOOD third-party games do not sell on the Wii. Nobody questioned that gaming pearls like Mario&Sonic or Carnival Games were selling like hotcakes.

(I mean of course you could say that there are not many good third-party games on Wii but that's a hen&egg problem)

Did you? Then you're still wrong :P